How do you calculate accounts recievable at the end of June 30th and explain how you got the answer ?

April	May	June	Total
$300,000	$500,000	$200,000	1,000,000

From past experience, the company has learned that 20% of a months sales are collected in the month of sale, another 70% are collected in the month following sale, and the remaining 10% are collected in the second month following sale. Bad debts are negligible and can be ignored. February sales totaled $230,000, and March sales totaled $260,000.