Question

Solve the system by substitution.

Answer 1

D x= -9
Y=9
Because 4(-9)+45=9
I just put in each one and d got it right.

Answer 2

Y = -x
y = 4x + 45

   -x = 4x + 45
- 4x  - 4x        
 -5x = 45
  -5     -5
    x = -9
y = 4x + 45
y = 4(-9) + 45
y = -36 + 45
y = 9
(x, y) = (-9, 9)

It is equal to B.