Not sure which dimension is which. Normally, the square footage of a room is calculated from its length and width, and not height. However, this question gives depth! Is it a dungeon?
Anyway, assuming that the depth is the height, the square footage is 20*15 = 300 sq ft
20ft * 15ft = 300 square feet.
18ft*20ft = 360 square feet
Perimeter = 20+20+15+15 = 70 feet
simply multiply. A linear foot in either direction is still a foot. Foot times foot equals square feet. That's 225 square feet.
All you need to do is multiply the length by the width, and it doesn't matter in what order you do it. 20ft X30ft= 600 square feet.
20ft * 15ft = 300 square feet.
300 square feet. To calculate square feet simply multiply length by width - the result is the area in square feet.
400 square feet
15ft X 52ft equals 780 square feet.
18ft*20ft = 360 square feet
If that is 20ft by 20ft then there are 400 square feet
Perimeter = 20+20+15+15 = 70 feet
375 square feet
simply multiply. A linear foot in either direction is still a foot. Foot times foot equals square feet. That's 225 square feet.
All you need to do is multiply the length by the width, and it doesn't matter in what order you do it. 20ft X30ft= 600 square feet.
420 square feet. (21 x 20 = 420)
20 feet x 10 feet = 200 square feet