All you need to do here is know where and how to plug in the numbers. In each equation, you'll have an initial fee, and an hourly fee, so your equation will be
y = i + hx, where i = the initial fee, and h = the hourly fee
So, after plugging them in, here's what you get:
Doors Galore: y = 40 + 50x
G&H: y = 60 + 40x