(URGENT) precalc final need urgent help

Simplify (a/b - b/a) times (a - a^2/a+b) a - a^2/a=b is a mixed number

An architect is designing a water fountain for a park she uses the given function to model the water jet flowing from the fountain nozzles where h(x) gives the height of the water jugs in feet x feet from the starting point h(x)=-1/20x+x+15

Place the following steps in order to complete the square and solve the quadratic equation,