3/10 EOM - this means the buyer will receive a cash discount of 3% if the bill is paid within 10 days after the end of the month indicated on the invoice date.

If an invoice is received on or before the 25th day of the month, payment is due on the 10th day of the next calendar month.

If a proper invoice is received after the 25th day of the month, payment is due on the 10th day of the second calendar month.

The invoice is received on August 3 thus payment is due on 10 of September. This means the buyer will receive cash discount of 3% and the amount due is:

1260 - 0.03*1260 = 0.97*1260 = $1,222.20

1,222.20 is due.