4x=112
x=112/4 ( '/' means divide)
x=28
I solved with addition elimination, and matrices elimination and received the same answer. (0,0,-3) I hope that helps.
Answer:
C
Step-by-step explanation:
Calculate the slope m using the slope formula
m = 
with (x₁, y₁ ) = (4, 9) and (x₂, y₂ ) = (12, 20)
m =
=
→ C
Adding 4 to both side is wrong he has to be subtract 4 to both side