A man purchased an item for 4,400 that was marked up by 10%. what was the original price

If f(x) = x+8 and g(x) = 4x- 3, find (f+g)(x)

Can someone explain to me how to do

Atrain leaves little? rock, arkansas, and travels north at 90 kilometers per hour. another train leaves at the same time and travels south at 80 kilometers per hour. how long will it take before they are 680 kilometers? apart?