Quality Supplier, Inc., accepts cash or credit card payment from customers. During June, Quality provided $170,000 worth

Question:

Quality Supplier, Inc., accepts cash or credit card payment from customers. During June, Quality provided $170,000 worth of supplies to customers who used Discover cards to pay for their purchases. Discover charges Quality Supplier 3% of sales for card services. Use the accounting equation to show how Quality Supplier will record these sales.
Why would Quality Supplier accept Discover cards?