A=(b+c)/b
Express b in terms of A and c
A=(b+c)/b split the right side into two fractions
A = b/b + c/b
A= 1 + c/b subtract 1 from both sides
A - 1 = c/b which means that
1 / [A -1] = b/c multiply both sides by c
c / [ A - 1] = b
