The final answer is (65, 60).
x + y = 125
- y - y
-------------------
x = 125 - y
12(125 - y) + 6y = 1140
1,500 - 12y + 6y = 1,140
1,500 - 6y = 1,140
- 1,500 - 1,500
------------------------------
-6y = -360
------- --------
-6 -6
y = 60
x + 60 = 125
- 60 - 60
-------------------
x = 65
