Surface area - math
posted by Please help me }: .
A cylindrical water tank is located on level ground. The tank has a height of 49 feet and a diameter of 42 feet. If one gallon of paint covers 350 square feet, how many gallons of paint are required to paint the water tank?
i tried: 2π⋅21⋅49 + 2π21^2 and then divided that by 350 but i got marked wrong
thanks for looking