PLZ HELP!

What is the rule for the function that is graphed?

y = 2 x + 2

y = 3 x + 2

y = 2 x

y = x – 2

For f(x) = 3x+1 and g(x) = x2 - 6, find (g/f)(x)

Emily is entering a bicycle race for charity. her mother pledges $0.90 for every 0.75 mile she bikes. if emily bikes 18 miles, how much will her mother donate?

Having a hard time understanding this question (see attachment).