Goofy substitute 5 in the x place instead of the y place. It says that y = 5 so Goofy suppose to substitute 5 in the y place. 4x + 3(5) = 51.
4x + 3(5) = 51
4x + 15 = 51
-15 -15
4x = 36
4x/4 = 36/4
x = 9
You plug the 9 in the x place for the second equation.
4(9) + 3y = 51
36 + 3y = 51
-36 -36
3y = 15
3y/3 = 15/3
y = 5
The solution is (9,5)
