um i am very confused about how do u multiple decimals like this question 6000 x 0.15 here how do i get the answer 900.

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

Math i have no idea how to do a and b

If f(x) = -5x + 1 and g(x) = x3, what is (gºf)(0)? enter the correct answer