how can i solve this using cocalc?

Suppose that you owe $3,000 on a credit card that charges a 16% annual interest rate compounded monthly. The card comes with an offer that allows you to make interest only payments for 6 months (that is, you only pay enough to pay off the interest per month). After the 6 month period, the remaining balance must be payed off over the course of 18 months in equal installments. Determine the size of the monthly payment during those 18 months where you are paying off the balance on your credit card. Comn