Basically, your CC is (if normal) compounded monthly, based on a yearly APR.
To calculate the amount of interest you'd pay on each of these accounts in a year, pull up a spreadsheet like Office Excel. Put in your current balance, then multiply it by the annual interest rate divided by 12, and add that quantity to the balance. Subtract any payment you make, and the result is your new balance. You can project this out for several months to get a good estimate of what you'll pay; in accounting or finance terms, what you're creating is an "amortization table". So, with a $10,000 balance, at 13.99% interest and making payments of $200/mo, the amortization table for one year's payments might look like:
Balance Interest Payment New Bal
$10,000.00 $116.58 -$200.00 $9,916.58
$9,916.58 $115.61 -$200.00 $9,832.19
$9,832.19 $114.63 -$200.00 $9,746.82
$9,746.82 $113.63 -$200.00 $9,660.45
$9,660.45 $112.62 -$200.00 $9,573.08
$9,573.08 $111.61 -$200.00 $9,484.68
$9,484.68 $110.58 -$200.00 $9,395.26
$9,395.26 $109.53 -$200.00 $9,304.79
$9,304.79 $108.48 -$200.00 $9,213.27
$9,213.27 $107.41 -$200.00 $9,120.68
$9,120.68 $106.33 -$200.00 $9,027.01
$9,027.01 $105.24 -$200.00 $8,932.25
As you can see, $200 isn't paying down this card very quickly. In one year, you will have paid $2,400, of which $1,332.25 went straight into the bank's pockets in interest charges, reducing your balance by only $1,067.75. Up the payments to $300/mo, and in 1 year you will have paid $3,600, and only been charged $1,252.24 in interest, so you'll have reduced your balance by $2,347.76 to only $7,652.24, which further reduces interest charges down the line. You can track the differences in the Excel sheet and play "what-ifs" very easily to see the ramifications of spending your $5,000 in various ways.
Understand that although, for instance, 13.99% may be your base interest rate, if the account has become delinquent, or you made any cash advances or balance transfers, higher or lower interest rates may be charged on a portion of the balance or the entire balance, depending on what's going on with your account; a balance transfer may get 0% interest for a year, then 19.99% interest after that if not paid off. Cash advances are ALWAYS charged at exorbitantly high rates, up to 40% APR.
Most credit card bills will include what may be called an "effective APR", which is a weighted average APR of all the various sub-balances of your account and the interest rates they currently have. Understand that your payment first pays off interest accrued during the past cycle, then pays down the principal on the highest-interest portion of the balance first, so if you have made a balance transfer to another card and are using that card for purchases, the only way to avoid interest on the transfer at the post-incentive rates is to pay off the ENTIRE balance in a year.
The minimum payment on a credit card USED to be just the amount of accrued interest or sometimes even less; if you paid only the minimum payment, the balance would never decrease (and may increase). In the wake of the 2008 credit crisis, most banks now enforce a higher minimum payment such that you would pay off the balance in between 3 and 5 years by making only minimum payments. This isn't strictly required AFAIK, but because banks ARE required by the CARD Act to disclose the payoff period at the minimum payment (which would be "never" under most previous policies), the higher minimum payments give cardholders hope that as long as they make the minimum payments and don't charge any more to the card, they will get back to zero.
