1. maths in a program

Hi guys.
I know this isn't code but maths to go into a program, I need to know which is right.

I have a couple of formulae which need rearranging:

1) Make r the subject of.
a = 2pi(r + h)

first multiply out the bracket 2pir + 2pih = a

then subtract 2pih from both sides 2pir = a - 2pih

now divide both sides by 2pi r = a - 2pih / 2ip ( this is the answer that I have ).

2) make x the subject of.
5(x + 2) = y

first multiply out the bracket 5x + 10 = y

then subtract 10 from both sides 5x = y - 10

now divide both sides by 5 x = y - 10 / 5 ( stop here with this answer or do the maths on the right hand side giving x = y / 5 - 2 ) where do I stop with the answer.

in question 1 I stopped as soon as the required subject was on its own but in question 2 i got the required subject on its own and then proceeded to simplify the maths on the rhs (which way is correct)

THANKS for the help (learner wanting to be a master).

2. Firstly, you went the long way around to get 'r' and 'x' the subjects.

a= 2pi(r + h)
a/2pi = r+h
r = a/2pi -h

5(x + 2) = y
x + 2 = y/5
x = y/5 - 2

Simple. But if you understand the other way better stick to that. Second, if 'x' is the subject to be, go all the way, don't stop halfway through.

3. anthony,