a pet store buys a new dog and cat washing station costing $7,000 with an 8.1% installment note. The note will be paid off with payments made at the end of each quarter over two years. Each payment is $956.60.

What I'm trying to figure out is what is the fraction... because they say end of each quarter over two years so what fraction would that be? I want to know because I'm creating a Amortisation table and I need the time in order to find the interest payment.