What is the y-intercept of the graph below?

If f(x)=2x-6 and g(x)=3x+9, find (f-g)(x)

How do i do this? i don’t understand

Zoey made 5 1/2 cups of trail mix for a camping trip. she wants to divide the trail mix into 3/4 cup servings. a. ten people are going on the trip. can zoey make enough 3/4 cup servings so that each person gets one serving? b. what size would the servings need to be for everyone to have a serving?