system of equaitons

Question

Using the system of equations below, which expression can be correctly substituted
for y in the equation 3x + 5y = 7?
–2x – y = –10
3x + 5y = 7
A. –2x + 10
B. 2x – 10
C. –2x – 10
D. 2x + 10

Answer 1

 

So really what they are asking is to solve  -2x - y = -10, for y.

 

 -2x - y = -10

  2x + y = 10

          y  = 10 - 2x  (choice A)