Answer:
Solve equation [2] for the variable y
[2] y = 8x + 7
// Plug this in for variable y in equation [1]
[1] 4x - 5•(8x+7) = -9
[1] -36x = 26
// Solve equation [1] for the variable x
[1] 36x = - 26
[1] x = - 13/18
// By now we know this much :
x = -13/18
y = 8x+7
// Use the x value to solve for y
y = 8(-13/18)+7 = 11/9
Solution :
{x,y} = {-13/18,11/9}