Acquarium A
First, let's find the area of the bottom
Area of the bottom = l x w = 4 x 2 = 8 square feet
Since Alice has 9 feet square and 9 is greater than 8, then Alice has enough to put the layer
Hence the answer is yes
Acquarium B
We need to find the area of the bottom of Acquarium B
Area = l x w = 6 x 3 = 18 square feet
Bob has 20 square feet to cover the bottom of aquarium B, since 20 is greater than 18, then Bob has enough layer to cover the bottom
Hence, the answer is yes
Acquarium C
let's first find the area of its bottom
Area = l x w = 3 x 2 = 6 square feet
Christy has 4 square feet to cover its bottom, but 4 is less than 6, hence he doesn't have enough pebble to cover its bottom
The answer is NO