Can someone please help with this? Honestly, I do not even know where to begin. Thank you!

Microbiotics currently sells all of its frozen dinners cash on delivery but believes it can* increase sales by offering supermarkets 1 month of free credit . The price per carton is $90 , and the cost per carton is $60 . The unit sales will increase from 1 , 190 cartons to 1 , 250 per month if credit is granted . Assume all customers pay their bills and take full advantage of any credit period offered ." a . If the interest rate is 1 % per month , what will be the change in the firm's total monthly profits on a present value basis if credit is offered to all customers ? ( Do not round* intermediate calculations . Round your answer to 2 decimal places . ) Change in total monthly profit* 6 . If the interest rate is 1 .5% per month , what will be the change in the firm's total monthly profits on a present value basis if credit is offered to all customers ? ( Do not round* intermediate calculations . Round your answer to 2 decimal places . Negative amount should be indicated by a minus sign . ) Change in total monthly profit* C . Assume the interest rate is 1 .5% per month but the firm can offer the credit only as a special deal to new customers , while existing customers will continue to pay cash on* delivery . What will be the change in the firm's total monthly profits on a present value basis under these conditions ? ( Do not round intermediate calculations . Round your answer to 2 decimal places . ) Change in total monthly profit