Need to understand a simplification problem for a literal algebraic equation

Question

Quite a simple question to be honest. I am trying to solve R = (D+a-b) /b for b.

An online tool that I have been using to help me out states that the first step in solving this equation is to simplify the right hand side by doing the following:

R = -1+ ((D+a) /b)

I am perplexed as to why -b has now suddenly been substituted by a -1 before the first term on the right side of the equation.

Any help would be greatly appreciated as I am tearing my hair out.

Answer 1

To answer your question about the other solution first: the -b in the numerator was divided by the b in the denominator and brought out of the fraction as -1...but I don't see that the elps much.

Clear fractions: Rb = D + a + b

Rb - b = D + a

b(R - 1) = D + a

b = (D + a)/(R - 1)

Answer 2

-b/b = -1

Sorry you are struggling. Hope this helps