How did they create this general journal ledger?

Plattsburg Plastics Corporation manufactures a variety of plastic products, including a series of molded chairs. The three models of molded chairs, which are all variations of the same design, are Standard (can be stacked), Deluxe (with arms), and Executive (with arms and padding). The company uses batch manufacturing and has an operation-costing system. The production process includes an extrusion operation and subsequent operations to form, trim, and finish the chairs. Plastic sheets are produced by the extrusion operation, some of which are sold directly to other manufacturers. During the forming operation, the remaining plastic sheets are molded into chair seats and the legs are added; the Standard model is sold after this operation. During the trim operation, the arms are added to the Deluxe and Executive models and the chair edges are smoothed. Only the Executive model enters the finish operation where the padding is added. All of the units produced receive the same steps within each operation. The March production run had a total manufacturing cost of $1,347,000. The units of production and direct-material costs incurred were as follows:

Units ProducedExtrusion MaterialsFormMaterialsTrimMaterialsFinishMaterialsPlastic sheets10,000$90,000Standard model12,000108,000$36,000Deluxe model6,00054,00018,000$13,500Executive model4,00036,00012,0009,000$18,000Total32,000$288,000$66,000$22,500$18,000

Manufacturing costs applied during the month of March were as follows:

Extrusion OperationForm OperationTrim OperationFinish OperationDirect labor$228,000$90,000$45,000$27,000Manufacturing overhead360,000108,00058,50036,000