6.3781 ∙ 10^3 kilometers write in scientific form

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

What is the product? a-3/15a × 5/a-3

Using inductive reasoning, what are the next two number in this set? 2,3/2,4/3,5/4,