(Cross multiplication) Please help I really need it

Awindow washer cleans 42 windows in 2 hours. at this rate, how many windows did he clean in 180 minutes.

Pamela has a 30-year, 5.75% mortgage on her $250,000 home. she has been paying on it for 5 years, and has recently hit some financial trouble. if her lender agreed to lower the interest rate on her $231,905.47 balance to 5.5%, what will her new payment be for the remainder of the loan?

If p(x) is the total value of the production when there are x workers in a plant, then the average productivity of the workforce at the plant is a(x) = p(x) x . (a) find a'(x). a'(x) = xp'(x) − p(x) x a'(x) = xp'(x) − p(x) x2 a'(x) = p'(x) − p(x) x a'(x) = xp'(x) − p'(x) x2 a'(x) = p'(x) − xp(x) x2 why does the company want to hire more workers if a'(x) > 0? a'(x) > 0 ⇒ a(x) is ; that is, the average productivity as the size of the workforce increases. (b) if p'(x) is greater than the average productivity, which of the following must be true? p'(x) − xp(x) > 0 p'(x) − xp(x) < 0 xp'(x) − p'(x) > 0 xp'(x) − p(x) < 0 xp'(x) − p(x) > 0