Answer part C, please!

Thank you!

2. Joe needs to purchase malt for his micro-brew production. His supplier charges $35 per delivery (no matter how much is delivered) and $1.20 per gallon. Joe's annual holding cost per unit is 35% of the dollar value of the unit. Joe uses 5,000 gallons of malt per week. a. How many gallons should Joe order from his supplier with each order? b. Suppose Joe were to order 3,800 gallons each time he orders. How many orders per year would he place on average? c. If Joe places an order for 15,000 gallons, then he will receive a 4% discount off the regular price of $1.20. If Joe were to do this with each order, what would be his average weekly total cost in $'s)? Don't forget to include the cost to purchase the units, the delivery charges and inventory holding costs