Answer:
(x, y) = (-4, -15)
Explanation:
Perhaps you want the solution to ...
y = 3/4x -12
y = -4x -31
Equating the two expressions for y gives ...
3/4x -12 = -4x -31
3/4x = -4x -19 . . . . . add 12
3x = -16x -76 . . . . . multiply by 4
19x = -76 . . . . . . . . . add 16x
x = -76/19 = -4 . . . . divide by 19
y = (3/4)(-4) -12 = -15 . . . . use the first equation to find y
The solution to this system of equations is ...
(x, y) = (-4, -15)