when solving, how do we get the number 75%?

On June 30,2012 , a company is preparing the cash budget for the third quarter. The collection pattern for credit sales has been 60% in the month of sale, 30% in the first month after sale, and the rest in the second month after sale. Uncollectible accounts are negligible. There are cash sales each month equal to 25% of total sales. The total sales for the quarter are estimated as follows: July, $30,000; August, $15,000; September, $35,000. Accounts receivable on June 30,2012 were $10,000. What amount would be the projected cash receipts for September? \begin{tabular}{|l|l|} \hline$28,500 \\ $30,125 \\ $37,250 \\ $21,375 \\ \hline \end{tabular}