how the answer come?

Moon company has an average selling price of OMR 20 per unit and an average variable cost of OMR 13 per unit. Current month's operating income is OMR 150,000. During the next month, the sales is expected to decrease by 4,500 units. What is the expected operating income for the next month? Select one: O a. OMR 118,500 O b. OMR 115,000 O c. OMR 111,500 O d. None of the answers given O e. OMR 181,500