can someone help me with this problem im not too sure how to get this

i was able to figure out everything except for the last question 3-b

Griswold's began operations in January, selling inexpensive sunglasses to large retailers like Walgreens and other smaller stores. Assume the following transactions occurred during its first six months of operations. Sold merchandise to Walgreens for $30,000; the cost of these goods to Griswold's was $21,000 Received payment in full from Walgreens. Sold merchandise to Bravis Pharmaco on account for $4,000; the cost of these goods to Griswold's was $1,900 Sold merchandise to Tony's Pharmacy on account for $9,000. The cost to Griswold's was $4,900 Sold merchandise to Anjuli Stores on account for $3,000; the cost to Griswold's was $1,700 Received $7,000 on account from Tony's Pharmacy. January 1 February 12 March 1 April 1 ay June 17 Required: 1. Complete the following aged listing of customer accounts at June 30. Unpaid Since May April March Greater than Three Months June Customer Total Balance (One Month) (Two Months) (Three Months) Anjuli Stores Bravis Pharmaco Tony s Pharmacy Walgreens Total 3,000 3,000 4.000 4,000