How do you represent each answer as an algebraic expression using the variable mentioned?

Question

A utility company measures gas consumption by the hundred cubic feet, CCF. The company has a three-step rate schedule for gas customers. First, there is a minimum charge of $5.00 per month for up to 3 CCF of gas used. Then, for the next 6 CCF, the charge is $0.75 per CCF. Finally, after 9 CCF, the charge is $0.55 per CCF. Represent the cost of "g" CCF of gas if "g" is greater than 9. Please help...

Answer 1

Let's summarize the question:
0 < g ≤ 3 : cost = 5
when g=3 : cost = 5
3 < g ≤ 9 : cost = 5 + 0.75*(g-3)
when g=9 : cost = 5 + 0.75*6 = 9.60
9 < g : cost = 9.60 + 0.55*(g-9)

Simplify the last expression:
For g≥9 CCF:
cost = 9.60 + 0.55(g-9)
=4.55 + 0.55g