Reorder the terms
112 + 3x = 100 + 5x
112 + 3x + (-5x) = 100 + 5x + (-5x)
Combine the like terms
5x + (-5x) = 0
112 + (-2x) = 100 + 0
112 + (-2x) = 100
112 + (-112) + (-2x) = 100 + (-112)
Combine like terms again
112 + (-112) =0
0 + (-2x) = 100 + (-112)
100 + (-112) = (-112) = (-12)
-2x = -12
-12 / -2 = 6
x = 6 ✓
Check your work
3 * 6 + 112 = 130
5 * 6 + 110 = 130
130 = 130 ✓