6/7 at the power of 2 value

PLZ BE HONEST I SPENT 75 POINTS ON THIS

In the polynomial below, what number should replace the question mark to produce a difference of squares? x2 + ? x - 36

You're locked out of your house. the only open window is on the second floor, 25 feet above the ground. there are bushes along the edge of the house, so you will need to place the ladder 10 feet from the house. what length ladder do you need to reach the window?

Common binomial factor of 6x(3x+7)+5(3x+7)