Explanation for Question 26 From the Math (Calc) Section on the 2018 March Sat
Question 26 says in the system of equations above a is a constant, 2 what is the Y value of the solution to the system in terms of 3 a so, because we're solving for the Y value of the solution, 4 I'm going to set up this system of equations so that the X values 5 are opposites. So I'm going to multiply the top one by three and the 6 bottom one by five. 7 So three times five X, 15 X plus three, 8 Y is equal to three. 9 And then the bottom one becomes negative 15 X plus negative 10. 10 Y is equal to 25. 11 Then I can add these together and I get zero X plus negative seven. 12 Y is equal to 25 plus 13 three. And then finally I can divide both sides by negative seven 14 to get Y is equal to negative 25 minus three, 15 over seven, which is answer choice a.