How many gallons of paint are needed to paint the walls of a rectangular prism shaped room that is 20 feet by 13 feet and 8 feet high if 1 gallon of paint covers 40 square feet?

  13.2 gallons

Step-by-step explanation:

The wall area is the product of the room's perimeter length and the wall height:

  A = Ph = (2(L+W))h = 2(20 +13)(8) = 528 . . . . square feet

The number of gallons required to cover this area is then ...

  (528 ft^2)/(40 ft^2/gal) = 13.2 gal

13.2 gallons of paint are required to paint the walls of the room.

to find the total number of combinations, multiply the quantity of each item by each other:

2 pairs of shoes x 3 pairs of shorts = 6 different combinations.