how do you rearrange ab-ex=e to make b the subject of the formlar and ab-ex=e to make e the subject?

Answer 1

As you would realise you need to have all but the b on the RHS of the formula.
So First add ex to BS of the equation. You get ab = e + ex
You want to move the 'a' now so devide BS by a. You get
b = (e + ex)/a


ab = e(1 + x) gather like terms
devide BS by (1=x)

e = ab/ (1+x)
simple.

Answer 2

1. ab-ex=e
ab=e+ex
b=(e+ex)/a

2. ab-ex=e
e+ex=ab
e(1+x)=ab
e=ab/(1+x)