If you would like to solve the system of equations, you can do this using the following steps:
x - 3y = 12 ... x = 12 + 3y
2x + 6y = 60
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2x + 6y = 60
2 * (12 + 3y) + 6y = 60
24 + 6y + 6y = 60
12y = 60 - 24
12y = 36
y = 36/12
y = 3
x = 12 + 3y = 12 + 3 * 3 = 12 + 9 = 21
(x, y) = (21, 3)
The correct result would be (21, 3).
