Finding unknown amounts

An auditor for the Internal Revenue Service is trying to reconstruct some partially destroyed records of two taxpayers. For each of the cases in the accompanying list, find the unknowns designated by the letters A through D.

Case 1
(in thousands) Case 2
Accounts receivable, 12/31 $ 9,000 $ 3,150
Cost of goods sold A 30,000
Accounts payable, 1/1 4,500 2,550
Accounts payable, 12/31 2,700 2,250
Finished goods inventory, 12/31 B 7,950
Gross margin 16,950 C
Work-in-process inventory, 1/1 0 1,200
Work-in-process inventory, 12/31 0 4,500
Finished goods inventory, 1/1 6,000 6,000
Direct materials used 12,000 18,000
Direct manufacturing labor 4,500 7,500
Manufacturing overhead costs 10,500 D
Purchases of direct materials 13,500 10,500
Revenues 48,000 47,700
Accounts receivable, 1/1 3,000 2,100

Let G = given, I = inferred
Step 1: Use gross margin formula Case 1 Case 2
Revenues $48,000 G $47,700 G
Cost of goods sold A 31,050 I 30,000 G
Gross margin $16,950 G C $17,700 I

Step 2: Use schedule of cost of goods manufactured formula
Direct materials used $12,000 G $18,000 G
Direct manufacturing labor costs 4,500 G 7,500 G
Indirect manufacturing costs 10,500 G D 9,750 I
Manufacturing costs incurred 27,000 I 35,250 I
Add beginning work in process, 1/1 0 G 1,200 G
Total manufacturing costs to account for 27,000 I 36,450 I
Deduct ending work in process, 12/31 0 G 4,500 G
Cost of goods manufactured $27,000 I $31,950 I

Step 3: Use cost of goods sold formula
Beginning finished goods inventory, 1/1 $ 6,000 G $ 6,000 G
Cost of goods manufactured 27,000 I 31,950 I
Cost of goods available for sale 33,000 I 37,950 I
Ending finished goods inventory, 12/31 B 1,950 I 7,950 G
Cost of goods sold $31,050 I $30,000 G
For case 1, do steps 1, 2, and 3 in order.
For case 2, do steps 1, 3, and then 2.