***PLEASE ANSWER ALL 3 QUESTIONS AND SHOW THE WORK. THANK YOU!

Rob owns an ice cream shop. Looking at last year's utility bills, the highest utility bill was $8000 for 4000 machine hours. The lowest utility bill was $5000 for 2400 machine hours. 1 Calculate the variable rate per machine hour and the total fixed utility cost. 2 Show the equation for determining total utility costs. 3 If Rob plans on using 3000 machine hours, what will the total utility bill be using the equation in part 2