From a solid cylinder whose height is 12cm and diameter 10cm, a conical cavity of same height and diameter is hollowed out. find the total surface area of the remaining solid.

Sanderson is having trouble with his assignment. his shown work is as follows: − 3 7 7 3 = − 3 7 × 7 3 = − 21 21 = −1 however, his answer does not match the answer that his teacher gives him. complete the description of sanderson's mistake. find the correct answer.