Budgeting process

Sir John
Kindly help with this question and the logic in solving it please. It is from BPP revision kit.

The following details has been extracted from the receivable collection records of C Co.

Invoice paid in the month after sales – 60%
Invoice pd in the 2nd month after sales – 25%
Invoice paid in the 3rd month after sale – 12%
Bad debt – 3%

Invoice are issued on the last day of each month. Customers paying in the month after are entitled to deduct a 2% settlement discount. Credit sales value for June to Sept are budgeted as follows:

June. July Aug. Sept
$35,000. $40,000. $60,000. $45,0000

What is the amount budgeted to be received from credit sales in Sept.

Answer is $49,480

Kindly explain the logic behind making the month after sales to be August and why 2nd month is July n 3rd June. I was of the opinion that it should be June to August, not August back to June.

Thanks for your time on this.