Whats the answer to these geometry problems? (show how plz)?

Question

1. Circumference of a circle - Solve for r: C = 2(pi)r

2. Volume of a cone - Solve for h: V = (1/3)(pi)r^2h

3. Surface area of a prism - Solve for L: S = 2wL + 2Lh + 2wh

Answer 1

1 c/2(pi)=2(pi)r/2(pi)          //////////////////////divide both sides by 2(pi)

c/2 (pi)=r

2. v / (1/3)(pi)r^2 = (1/3)(pi)r^2h / (1/3)(pi)r^2      //////////////////divide both sides by (1/3)(pi)r^2

v / (1/3)(pi)r^2=h

3. S - 2wh = 2wL + 2Lh  ////////////// subtract 2wh

S - 2wh =  L (2w + 2h) ////////////// divide by (2w + 2h)

(S - 2wh) / (2w + 2h) = L