$1.$Collected $$200$ cash from customers for services performed in August.

$2.$Collected $$500$ cash from customers for services performed in September.

$3.$Billed customers $$600$ for services performed in September.

$4.$Performed $$100$ of services to customers who paid in advance in August.

$5.$Received $$100$ from customers in advance for services to be performed in

October.

$($a$)$ Calculate revenue for the month of September using the accrual basis of

accounting.

$($b$)$ Calculate revenue for the month of September using the cash basis of

accounting.