The Ski Shop received an invoice for $9600 dated August 11, terms 5/10, 2/30, n/90, for a

Question:

The Ski Shop received an invoice for $9600 dated August 11, terms 5/10, 2/30, n/90, for a shipment of skis. The Ski Shop made two partial payments.
(a) How much was paid on August 20 to reduce the unpaid balance to $7000?
(b) How much was paid on September 10 to reduce the outstanding balance by $3000?
(c) What is the remaining balance on September 10?