The function C(x)=-5x+625 represents the cost to produce x number of items. How many items should be produced so that the average cost is less than $20?

Can someone answer these problems for me

For g(x) = 5x - 3 and h(x) = [tex]\sqrt{x}[/tex], find (g · h)(4)

If the altitude is drawn to the hypotenuse of a right triangle, then the two triangles formed are similar to the original triangle and to each other. which set of triangles shows the similar triangles created by the altitude in the diagram?