please help me understand the formula used to find the transportation cost in this excel table

You manage a production line at a truck manufacturing plant. Your company typically uses 550 cases of machine sealant a month in your manufacturing process. Each case weighs 12 pounds. You typically buy your sealant monthly to reduce your inventory carrying costs, which runs at 32% per year. An accountant has suggested that you could buy the product using a forward buy as a part of a mixed buying strategy. You know that it costs you $145 to make an order with the company that sells the sealant. You have also checked with the sealant seller who adds a transportation charge to the order. The transportation rate is $78 cwt for shipments less than 10,000 pounds, $67/ cwt for shipments less than 20,000 pounds, and $59/cwt for shipments 20,000 pounds or more. The sealant seller has provided the attached table with the expected costs for a case of machine sealant for the next year. Prepare a one to two paragraph explanation of the benefits and risks of the forward buy strategy to present to upper management. [5 points] Based upon this information, calculate the cost of the current strategy (buying monthly) as well as a mixed buying strategy using 2-month and 3-month forward buying concepts. Which strategy do you recommend and why? The submission is to be typed. [15 points] You manage a production line at a truck manufacturing plant. Your company typically uses 550 cases of machine sealant a month in your manufacturing process. Each case weighs 12 pounds. You typically buy your sealant monthly to reduce your inventory carrying costs, which runs at 32% per year. An accountant has suggested that you could buy the product using a forward buy as a part of a mixed buying strategy. You know that it costs you $145 to make an order with the company that sells the sealant. You have also checked with the sealant seller who adds a transportation charge to the order. The transportation rate is $78 cwt for shipments less than 10,000 pounds, $67/ cwt for shipments less than 20,000 pounds, and $59/cwt for shipments 20,000 pounds or more. The sealant seller has provided the attached table with the expected costs for a case of machine sealant for the next year. Prepare a one to two paragraph explanation of the benefits and risks of the forward buy strategy to present to upper management. [5 points] Based upon this information, calculate the cost of the current strategy (buying monthly) as well as a mixed buying strategy using 2-month and 3-month forward buying concepts. Which strategy do you recommend and why? The submission is to be typed. [15 points]