20*20 square feet tile = 400 square feet, so in principle, two tiles will cover 800 square feet, which is more than enough. This is provided that the offcuts can be used.
15
42
abswer is 6.9218 square feet
10
15 exactly !
240
15
42
180
abswer is 6.9218 square feet
15 exactly !
10
As 8 feet x 8 feet = 64 square feet it will only take one 8 feet by 8 feet tile to cover 64 square feet.
Thirteen
192 tiles
16x16 square feet = 256 square feet, so two tiles will suffice.
A 2ft x 2ft square is 4 square feet and 42 squares will be needed to cover 168 square feet.