A rectangular tank needs to be coated with insulation. The tank has dimensions of 3 feet, 7 feet, and 2 feet. Each square foot of insulation costs $20. How much will it cost to cover the surface of the tank with insulation?
Choose the correct choice from the following choices:
A) $ 880
B) $ 1050
C) $ 1280
D) $ 1460
E) $ 1640

Rationale: "the total surface area is 2 ( 2 * 3 + 3 * 7 + 2 * 7 ) = 82 square feet the total cost is 82 * $ 20 = $ 1640 the answer is e ."
Answer: E