Given that a side length is that means its parallel side is also 16. So 16 + 16 is 32 and 72 - 32 is 40 and 40 divided by 2, for two sides of the rectangle youll get 20. With the length being 20 and width being 16, 20 times 16 will get you 320m^2 which is the area.
Ok so what you're trying to do is get L by itself so to do this you move everything to the other side:
A=L*WH
=L
So you answer would be:
C
For deck,
Length = 2x + 1
Width = 5x + 2
For pool,
Length = 2x
Area of deck including pool = (2x + 1)(5x + 2) = 10x^2 + 4x + 5x + 2 = 10x^2 + 9x + 2
Area of pool = 2x * 2x = 4x^2
Area of only the deck = 10x^2 + 9x + 2 - 4x^2
= 6x^2 + 9x + 2
The answer is 21 as there are 7 toppings and u can only put two toppings on each pizza so in the end u hv to do 7 * 3 to get 21