(a) To find the area of the kitchen floor, we just have to multiply
[tex]A=16ft\times20ft=320ft^2[/tex](b) To find the number of tiles needed, we have to find the area of each tile, which is
[tex]A_{\text{tile}}=2ft^{}\times2ft^{}=4ft^2[/tex]Then, we divide the total area of the kitchen floor by the area of each tile.
[tex]n=\frac{320ft^2}{4ft^2}=80[/tex]Hence, David will need 80 tiles to cover the floor.