You multiply them together -
20 x 4 = 80 square feet
Read your own question! The square footage is 20!
400
80 sq ft
5' * 4' = 5*4 = 20 sq feet
420
400 square feet
if you want the square footage, 15 ft x 20 ft is 300 square feet
The question does not give the units of measurement for the room's size. Assuming they are feet, the square footage is 20*12 = 240 square feet.
If each side of the square is 20-ft, then the area of the square is (20 x 20) = 400 square feet.
15 * 20 = 300 square feet.
In terms of square footage, 20 acres = 871,200 square feet.
740