Explanation for Question 11 From the Math (Calc) Section on the 2018 May Sat
Question 11 says in the system of equations above what is the value of 2 X plus one? So I'm just going to start by multiplying this whole equation 3 by two, to get eight X plus two, 4 Y is equal to 34, 5 and then I'm going to subtract this equation above from that five X plus 6 two, Y is equal to 22, 8 X minus five. 7 X is equal to three X to Y minus two, 8 Y cancels out and 34 minus 22 is equal to 12. 9 Then I can divide both sides by three. And that tells me that X 10 is equal to four. Now I can take that and I can plug it 11 into four X plus Y equals 17, 12 which was one of our original equations defined what Y is four 13 times four 16, so 16 plus Y equals 17. 14 And when I subtract 16 from both sides, 15 I get Y is equal to one. So now I know that X is 16 equal to four. Y is equal one and therefore X plus Y is equal 17 to four plus one, which is five or answer choice a.