Question

A = h (a + b) for b.

Answer 1

first divide by h both sides then you have

A = a+b
---
h

Answer 2

then subtract a to isolate b so you ahve

A/h -a = b

Answer 3

so the answer will be b=(A-a)/h

Answer 4

no, that is not the same, the answer is

A/h -a = b

A
---- - a = b
h