2 short questions both needs to be answered with explanations and work done

7. Jie purchased a computer priced at $1423.42, financing it by paying $68.62 on the date of purchase, and signing a contract to pay equal monthly payments over the next eighteen months. If the terms of the contract state that interest is calculated at 9.2% compounded monthly, how much does Jie have to pay at the end of each month? Jie must make payments of $ (Round the final answer to the nearest cent as needed. Round all intermediate values to six decimal places as needed.) 8. Slicks Mechanics provides oil changes for vehicles for $30.68. For each vehicle, the cost of oil is $6.19 for the shop. Fixed costs for this type of service are $6759.24. How many oil changes need to be completed to break even? In order to break even, oil changes need to be completed. (Round up to the nearest unit.)