beginner needs help with basic math concepts

Hello,

I have an equation of the following form:

A=(B-alpha*C)/beta (where alpha and beta are known or unknown)

I want to obtain something of the following form:

A = ? * C (in other words expressing A in function of C)

My questions are as follows:
1. What is called the underlying maths concept of what I am trying to
achieve?
2. What is the corresponding maxima function and its syntax?

Thanks in advance,

Julien.