Pvaries directly with the square of d

I’m on question 7 it says a covered water tank is in the shape of a cylinder the tank has a 28 inch diameter and a height of 66 inches to the nearest square inch what is the surface area of the water tank

Similarly fie each expression 18,19,20

Troy has a 7/23 balloon mortgage on his $260,000 home. he has been making payments of $1323 each month and will have a balloon payment due for the amount of $198,569.