Solve for r

Question

S= a-Lr/1-r for r

Answer 1

The Expression is S = (a - Lr)/(1-r)

Multiply each side by (1 - r).

S(1 - r) = (a - Lr)

S - Sr = a - Lr

Re-write the expression such that alike terms are on one side.

S - a = Lr - Sr

S - a = r(L - S)

Divide each side by L-S.

r = (S - a)/(L - S)

Therefore r = (S - a)/(L - S).