The anwer on the practice is A) 33600 & B) 62000 but I don't understand how this was reached. Please give detailed answer as I don't understand at all

Thank You in advance

Question 1 - Relevant Costing - Accepting Special Order (10 marks) Following is the budgeted income statement for Karibu Inc.: $ 900,000 Sales (15,000 Units @ $60) Less: Cost of Goods Sold: $150,000 Direct Materials Direct Labour Variable Overhead Fixed Overhead $300,000 $60,000 $225,000 Cost of Goods Sold $735,000 $165,000 Gross Profit $18,000 Less: Operating Expenses: Sales Commission (2% of Sales) Delivery Expense (Var.) Sales Salaries (Fixed) Administrative (Fixed) Total Operating Expenses Operating Income $90,000 $30,000 $12,000 $150,000 $ 15,000 Additional Information: Maximum plant capacity = 18,000 units (it can be increased to 30,000 units for an additional cost of $ 28,000) Karibu Inc. received a special order from Habari Inc. to purchase 6,000 units @ $50 per unit. Habari Inc. will pay the delivery costs. The special order will not affect the demand from the regular customers and sales commissions will be paid on the special order. a. Assume that if Karibu accepted the special order, it will have to give up sales to its regular customers. What the net change in operating income if Karibu accepts the special order? Show your work for part marks. b. Assume that if Karibu accepted the special order, it will expand capacity to accommodate the special order. What is the net change in operating income if Karibu accepts the special order? Show your work for part marks