The height of a hill, h(x), in a painting can be written as a function of x, the distance from the left side of the painting. both h(x) and x are measured in inches.

I suspect there's more to this problem than you've shared.  Based only upon what you have shared:

"h(x) = the height, in inches) of the hill shown in the painting, where x is the distance from the left side of the painting of the point on the hill."

Double check to ensure that you've copied the entire problem to be solved.