Solve the system of equations below by using substitution

Question

8x-y=4

 

-8x-5y=2

Answer 1

(1)  8x - y = 4 ---> y = 8x - 4

 

(2)  -8x - 5y = 2 ---> -8x - 5(8x - 4) = 2 ---> -8x - 40x + 20 = 2

 

      ---> -48x = 2 - 20 ---> -48x = -18 ---> x = 18/48 = 3/8

 

      ---> y = 8x - 4 = 8(3/8) - 4 = 3 - 4 = -1