{"id":"cb_question_bank:a065a22a-bed3-4ccf-8969-ba6f5f4ff771","source_id":"cb_question_bank","source_item_id":"a065a22a-bed3-4ccf-8969-ba6f5f4ff771","external_id":"425d30d9-246b-4058-b45c-2e4168f92a0f","ibn":null,"question_id":"f718c9cf","program":"SAT","module":"math","domain_code":"H","domain":"Algebra","skill_code":"H.D.","skill":"Systems of two linear equations in two variables","difficulty":"H","score_band":6,"answer_type":"spr","answer_source":"key","layout_warning":null,"form_id":null,"module_number":null,"position":null,"stem":"5 x plus 14 y equals 45 10 x plus 7 y equals 27 The solution to the given system of equations is left parenthesis x comma y right parenthesis . What is the value of x y ?","stimulus":"","stimulus_html":null,"stem_html":"<p style=\"text-align: center;\"><math alttext=\"5 x plus 14 y equals 45\"><mrow>\n\t<mrow>\n\t\t<mrow>\n\t\t\t<mn>5</mn>\n\t\t\t<mi>x</mi>\n\t\t</mrow>\n\t\t<mo>+</mo>\n\t\t<mrow>\n\t\t\t<mn>14</mn>\n\t\t\t<mi>y</mi>\n\t\t</mrow>\n\t</mrow>\n\t<mo>=</mo>\n\t<mn>45</mn>\n</mrow>\n</math></p>\n<p style=\"text-align: center;\"><math alttext=\"10 x plus 7 y equals 27\"><mrow>\n\t<mrow>\n\t\t<mrow>\n\t\t\t<mn>10</mn>\n\t\t\t<mi>x</mi>\n\t\t</mrow>\n\t\t<mo>+</mo>\n\t\t<mrow>\n\t\t\t<mn>7</mn>\n\t\t\t<mi>y</mi>\n\t\t</mrow>\n\t</mrow>\n\t<mo>=</mo>\n\t<mn>27</mn>\n</mrow>\n</math></p>\n<p style=\"text-align: left;\">The solution to the given system of equations is&nbsp;<math alttext=\"left parenthesis x comma y right parenthesis\"><mfenced><mrow><mi>x</mi><mo>,</mo><mi>y</mi></mrow></mfenced></math>. What is the value of <math alttext=\"x y\"><mrow>\n\t<mi>x</mi>\n\t<mi>y</mi>\n</mrow>\n</math>?</p>","rationale_html":"<p style=\"text-align: left;\">The correct answer is <math alttext=\"nine fifths\"><mfrac>\n\t<mn>9</mn>\n\t<mn>5</mn>\n</mfrac>\n</math>. Multiplying the first equation in the given system by <math alttext=\"2\"><mn>2</mn>\n</math> yields <math alttext=\"10 x plus 28 y equals 90\"><mrow>\n\t<mrow>\n\t\t<mrow>\n\t\t\t<mn>10</mn>\n\t\t\t<mi>x</mi>\n\t\t</mrow>\n\t\t<mo>+</mo>\n\t\t<mrow>\n\t\t\t<mn>28</mn>\n\t\t\t<mi>y</mi>\n\t\t</mrow>\n\t</mrow>\n\t<mo>=</mo>\n\t<mn>90</mn>\n</mrow>\n</math>. Subtracting the second equation in the given system, <math alttext=\"10 x plus 7 y equals 27\"><mrow>\n\t<mrow>\n\t\t<mrow>\n\t\t\t<mn>10</mn>\n\t\t\t<mi>x</mi>\n\t\t</mrow>\n\t\t<mo>+</mo>\n\t\t<mrow>\n\t\t\t<mn>7</mn>\n\t\t\t<mi>y</mi>\n\t\t</mrow>\n\t</mrow>\n\t<mo>=</mo>\n\t<mn>27</mn>\n</mrow>\n</math>, from <math alttext=\"10 x plus 28 y equals 90\"><mrow>\n\t<mrow>\n\t\t<mrow>\n\t\t\t<mn>10</mn>\n\t\t\t<mi>x</mi>\n\t\t</mrow>\n\t\t<mo>+</mo>\n\t\t<mrow>\n\t\t\t<mn>28</mn>\n\t\t\t<mi>y</mi>\n\t\t</mrow>\n\t</mrow>\n\t<mo>=</mo>\n\t<mn>90</mn>\n</mrow>\n</math> yields <math alttext=\"left parenthesis 10 x plus 28 y right parenthesis minus left parenthesis 10 x plus 7 y right parenthesis equals 90 minus 27\"><mfenced><mrow><mn>10</mn><mi>x</mi><mo>+</mo><mn>28</mn><mi>y</mi></mrow></mfenced><mo>-</mo><mfenced><mrow><mn>10</mn><mi>x</mi><mo>+</mo><mn>7</mn><mi>y</mi></mrow></mfenced><mo>=</mo><mn>90</mn><mo>-</mo><mn>27</mn></math>, which is equivalent to <math alttext=\"10 x plus 28 y minus 10 x minus 7 y equals 63\"><mn>10</mn><mi>x</mi><mo>+</mo><mn>28</mn><mi>y</mi><mo>-</mo><mn>10</mn><mi>x</mi><mo>-</mo><mn>7</mn><mi>y</mi><mo>=</mo><mn>63</mn></math>, or <math alttext=\"21 y equals 63\"><mrow>\n\t<mrow>\n\t\t<mn>21</mn>\n\t\t<mi>y</mi>\n\t</mrow>\n\t<mo>=</mo>\n\t<mn>63</mn>\n</mrow>\n</math>. Dividing both sides of this equation by <math alttext=\"21\"><mn>21</mn>\n</math> yields <math alttext=\"y equals 3\"><mrow>\n\t<mi>y</mi>\n\t<mo>=</mo>\n\t<mn>3</mn>\n</mrow>\n</math>. The value of <math alttext=\"x\"><mi>x</mi>\n</math> can be found by substituting <math alttext=\"3\"><mn>3</mn>\n</math> for <math alttext=\"y\"><mi>y</mi>\n</math> in either of the two given equations. Substituting <math alttext=\"3\"><mn>3</mn>\n</math> for <math alttext=\"y\"><mi>y</mi>\n</math> in the equation <math alttext=\"10 x plus 7 y equals 27\"><mrow>\n\t<mrow>\n\t\t<mrow>\n\t\t\t<mn>10</mn>\n\t\t\t<mi>x</mi>\n\t\t</mrow>\n\t\t<mo>+</mo>\n\t\t<mrow>\n\t\t\t<mn>7</mn>\n\t\t\t<mi>y</mi>\n\t\t</mrow>\n\t</mrow>\n\t<mo>=</mo>\n\t<mn>27</mn>\n</mrow>\n</math> yields <math alttext=\"10 x plus 7 left parenthesis 3 right parenthesis equals 27\"><mn>10</mn><mi>x</mi><mo>+</mo><mn>7</mn><mfenced><mn>3</mn></mfenced><mo>=</mo><mn>27</mn></math>, or <math alttext=\"10 x plus 21 equals 27\"><mrow>\n\t<mrow>\n\t\t<mrow>\n\t\t\t<mn>10</mn>\n\t\t\t<mi>x</mi>\n\t\t</mrow>\n\t\t<mo>+</mo>\n\t\t<mn>21</mn>\n\t</mrow>\n\t<mo>=</mo>\n\t<mn>27</mn>\n</mrow>\n</math>. Subtracting <math alttext=\"21\"><mn>21</mn>\n</math> from both sides of this equation yields <math alttext=\"10 x equals 6\"><mrow>\n\t<mrow>\n\t\t<mn>10</mn>\n\t\t<mi>x</mi>\n\t</mrow>\n\t<mo>=</mo>\n\t<mn>6</mn>\n</mrow>\n</math>. Dividing both sides of this equation by <math alttext=\"10\"><mn>10</mn>\n</math> yields <math alttext=\"x equals six tenths\"><mi>x</mi><mo>=</mo><mfrac><mn>6</mn><mn>10</mn></mfrac></math>, or <math alttext=\"x equals three fifths\"><mrow>\n\t<mi>x</mi>\n\t<mo>=</mo>\n\t<mfrac>\n\t\t<mn>3</mn>\n\t\t<mn>5</mn>\n\t</mfrac>\n</mrow>\n</math>. Therefore, the value of <math alttext=\"x y\"><mrow>\n\t<mi>x</mi>\n\t<mi>y</mi>\n</mrow>\n</math> is <math alttext=\"left parenthesis three fifths right parenthesis left parenthesis 3 right parenthesis\"><mfenced><mfrac><mn>3</mn><mn>5</mn></mfrac></mfenced><mfenced><mn>3</mn></mfenced></math>, or <math alttext=\"nine fifths\"><mfrac><mn>9</mn><mn>5</mn></mfrac></math>. Note that 9/5 and 1.8 are examples of ways to enter a correct answer.</p>","correct_answer":["1.8","9/5"],"has_media":false,"has_mathml":true,"has_table":false,"source_created_at":"2023-08-02T20:25:59.818000+00:00","source_updated_at":"2023-08-02T20:25:59.818000+00:00","options":[],"attribution":{"source_id":"cb_question_bank","source_name":"College Board digital SAT question bank (community dump)","rights_holder":"College Board","canonical_url":"https://satsuitequestionbank.collegeboard.org/","retrieved_from":"https://raw.githubusercontent.com/mdn522/sat-question-bank/main/data/cb-digital-questions.json","attribution":"SAT practice questions © College Board, from the official SAT Suite Question Bank. Retrieved via the community dump at github.com/mdn522/sat-question-bank.","disclaimer":"SAT® and PSAT/NMSQT® are trademarks registered by the College Board, which is not affiliated with, does not sponsor, and does not endorse this project.","license":"College Board copyright; source repository carries no licence. Local use only.","redistributable":false,"item_count":2017}}