Ravenna Company is a merchandiser that uses the indirect method to prepare the operating activities section of its statement of cash flows. Its balance sheet for this year is as follows:

Ending Balance Beginning Balance

Cash $ 52,800 $ 62,700

Accounts receivable 45,100 48,400

Inventory 60,500 55,000

Total current assets 158,400 166,100

Property, plant, and equipment 165,000 154,000

Less accumulated depreciation 55,000 38,500

Net property, plant, and equipment 110,000 115,500

Total assets $ 268,400 $ 281,600

Accounts payable $ 35,200 $ 62,700

Income taxes payable 27,500 30,900

Bonds payable 66,000 55,000

Common stock 77,000 66,000

Retained earnings 62,700 67,000

Total liabilities and stockholders' equity $ 268,400 $ 281,600

During the year, Ravenna paid a $6,600 cash dividend and it sold a piece of equipment for $3,300 that had originally cost $6,600 and had accumulated depreciation of $4,400. The company did not retire any bonds or repurchase any of its own common stock during the year.

4-a. If the company debited Accounts Receivable and credited Sales for $660,000 during the year, what is the total amount of credits recorded in Accounts Receivable during the year?

4-b. What does the amount of these credits represent?