what would my monthly credit card payment be if I made a $2,800 purchase (that is what's remaining) and the interest rate is 20%?

A typical minimum credit card payment is 2% of the remaining principal each month, or a minimum amount (if 2% of the principal is below this amount, then the company just uses this amount instead)

First, apply the interest:  2800 * 0.2/12 = 280 * 2/12 = 280 * 1/6 = 140/3 = 46.6666.....

2846.6666.....

Take 2% of that

2846.666.... * 0.02 =>

28.466666.... * 2 =>

56.933333..... =>

57

2846.67 - 57 = 2789.67

Rinse, lather repeat.  At around $57 per month, it'll take you 104 months to pay it off

57 * 104 =>

5700 + 228 =>

5928

5928 - 2800 = 3128

You'll end up paying twice for this debt.  So what happens if you pay $60 per month?

Spending just $3 more per month will save you 13 months of payments and will save you about $500.

$70 per month will have the debt paid in 67 months and save you $1250.

https://www.bankrate.com/calculators/credit-cards/...

If you pay the whole amount before due date then you do not need to pay any interest on it.