238 + X = 915
X = 915 - 238
X = 677
-----------------
241 - A = 108
A = 241 - 108
A = 133
----------------
3125 = B - 104
B = 3125 + 104
B = 3229
-----------------
241 = 1005 - B
B = 1005 - 241
B = 764
-----------------
7100 = X + 3500
X = 7100 - 3500
X = 3600
-----------------
A - 315 = 490
A = 490 + 315
A = 805