12B-9. Can someone show me how to do this problem?

Will rate a thumb up for good response thanks so much (PLEASE CIRCLE OR HIGHLIGHT final answer thx)

Chris Sandvig Irrigation, Inc., has summarized the price list from four potential suppliers of an underground control valve. See the table below. Annual usage is 1,100 valves; order cost is $13 per order; and annual inventory holding costs are $2.15 per unit. Vendor A Quantity Price 1-49 $35.00 50-99 34.75 100-299 33.55 300-499 32.35 500-699 31.15 700+ 30.75 Vendor B Quantity Price 1-99 $34.75 100-299 34.00 300-499 32.80 500-699 31.60 700+ 30.50 Vendor C Quantity Price 1-149 $34.50 150-399 33.75 400-599 32.50 600+ 31.10 Vendor D Quantity Price 1-399 $34.25 400-599 33.00 600+ 31.00 Which vendor should be selected and what order quantity is best if Sandvig Irrigation wants to minimize total cost? Chris Sandvig Irrigation should order units at a time from (enter your response as a whole number). Vendor C Vendor B Vendor A Vendor D