Al is a physician who conducts his practice as a sole proprietor. During 2018, he received cash of $280,000 for medical services. Of the amount collected, $40,000 was for services provided in 2017. At the end of 2018, Al held accounts receivable of $60,000, all for services rendered in 2018. In addition, at the end of the year, Al received $12,000 as an advance payment from a health maintenance organization (HMO) for services to be rendered in 2019. Compute Al's gross income for 2018 using the:
a. Cash basis of accounting.
b. Accrual basis of accounting.