Select a linear cost function equation for each of the following conditions. Use y for estimated costs and X for activity of the cost driver.a.Direct materials cost is ​$1.40 per poundb.Total cost is fixed at $ 8 comma 500 per month regardless of the number of units produced.c.Auto rental has a fixed fee of ​$70.00 per day plus ​$2.00 per mile driven.d.Machine operating costs include ​$1 comma 600 of maintenance per​ month, and ​$10.00 of coolant usage costs for each day the machinery is in operation.