x+3/6 = x-6/3
3(x+3/6) = 3(x-6/3)
x+3/2= x-6
2(x+3/2) = 2(x-6)
x+3 = 2x-12
x+3-3 = 2x-12-3
x=2x-15
x-2x = 2x-15-2x
-x = -15
-1(-x) = -1(-15)
x=15
Check:
(15)+3/6 = (15)-6/3
18/6 = 9/3
3 = 3