Assume the mattress have no width, only length.
By Pythagoras' Theorem, √(72^2 + 80^2) = 107.6 inches.
8x²-18xy-5y²
8x²+2xy-20xy-5y²
2x(4x+y) -5y (4x+y)
= (2x-5y) (4x+y)
Answer: 
Step-by-step explanation:
We can use the following formula to solve this exercise:

In this case "T" is the time in hours it takes to both taps fill the pool working together, "A" is the time in hours for the first tap filling the pool alone an "B" is the time in hours for the second tap filling the pool alone.
We can identify that:

Then, we must subsitute the known values into the formula:

And finally we must solve for "B".
Then we get:
