help part A and part B please

B) What is the total cost of this policy? Total annual cost of ordering optimal size= $____ (round your response to the nearest whole number)

Rocky Mountain Tre Center selis 9,000 go-cart tires per year. The ordering cost for each order is $40, and the holding cost is 30% of the purchase price of the tires per year. The purchase price is $22 per tire if fewer than 200 tires are ordered, $16 per fire if 200 or more-but fower than 8,000 - tires are ordered, and $13 per tire if 8,000 or more tires are ordered. a) How many tires should Rocky Mountain order each time it places an order? Rocky Mountain's optimal order quantity is units (enter your response as a whole number)