Answer:
x = 8 and y = -4
Explanation:
3x + 4y = 8 (call this equation '1')
x - y = 12 (call this '2')
multiply '2' by 3:
3x - 3y = 36 (call this '3')
subtract '1' from '3':
(3x - 3y = 36) - (3x + 4y = 8)
0x + -7y = 28
-7y = 28
y = -4.
sub that back into '1':
3x + 4y = 8
3x + 4(-4) = 8
3x - 16 = 8
3x = 8 + 16 = 24
x = 8.
sub both y =-4 and x =8 into '2' to check if everything adds up:
x - y = 12
8 - -4 = 8 + 4 = 12
so x = 8 and y = -4