Question

S=L−rL

solve for r

Please solve this fast for much points.

Answer 1

Subtract L from both sides. 
the expression now becomes,
S−L=−rL
2)Divide by L on both sides.
S−LL=−r
3)Multiply with a negative sign on both sides in the final step to obtain the expression in terms of r      so the answer is #(L-S)/L = r#