(9x-2) - (5x+6) =
4x-8 , this is your profit function
No the side lengths of 9,12, and 18 doesn’t form a right triangle. Posted a picture showing all the side length that is a right triangle.
(-$11) x 12. That would be the equation because there are 12 months, so you would multiply -11 from 12 to get -132 every year for the tennis club membership.
Take the longer leg length as

Use the formular
∴ shorter leg = 32 - 8 = 24ft
longer leg = 32ft
hypotenuse = 32 + 8 = 40ft