Use the information in each of the following separate cases to calculate the unknown amount:

a. During October, Shandra Company had \($97,500\) of cash receipts and \($101,250\) of cash disbursements. The October 31 Cash balance was \($16,800.\) Determine how much cash the company had at the close of business on September 30.

b. On September 30, Li Ming Co. had a \($97,500\) balance in Accounts Receivable. During October, the company collected \($88,950\) from its credit customers. The October 31 balance in Accounts Receivable was \($100,500.\) Determine the amount of sales on account that occurred in October.

c. Nasser Co. had \($147,000\) of accounts payable on September 30 and \($136,500\) on October 31. Total purchases on account during October were \($270,000.\) Determine how much cash was paid on accounts payable during October.