Question

3b-4/2=c , for b

Answer 1

3b - (4/2) = c ......for b --- add 4/2 to both sides
3b = 4/2 + c --- reduce
3b = 2 + c -- divide both sides by 3
b = (2 + c)/3 or b = 2/3 + c/3

or if you mean...
(3b - 4) / 2 = c --- multiply both sides by 2
3b - 4 = 2c --- subtract 4 from both sides
3b = 2c - 4 -- divide by 3 on both sides
b = (2c - 4) / 3 or b = 2/3c - 4/3