Answer:
x = -3, y = 7.
Explanation:
x + 3y = 18
-3x - 12y = -75
Multiply the first equation by 3:
3x + 9y = 54
Adding the last 2 equations to eliminate x:
-3y = -21
y = 7.
Substitute y = 7 into the first equation:
x + 3(7) = 18
x + 21 = 18
x = 18 - 21
x = -3.