Al is a medical doctor who conducts his practice as a sole proprietor. During 2016, he received cash of $493,800 for medical services. Of the amount collected, $42,000 was for services provided in 2015. At the end of 2016, Al had accounts receivable of $93,100, all for services rendered in 2016. In addition, at the end of the year, Al received $13,000 as an advance payment from a health maintenance organization (HMO) for services to be rendered in 2017. Compute Al's gross income for 2016:

B. Using the accrual basis of accounting.