To clear 20k of debt you should pay as much as possible towards the 20K of debt and make more than the minimum payment or double up on payments towards the 20K debt to pay it back sooner.
For most people it can take 8 to 10 years to pay back 20K of debt but if you can afford the extra payments you can get it paid off sooner.
The longer a loan is out or credit card is out the more interest is charged so you would pay more in interest over the time that you have the loan out or credit card out.
Making double payments or more can help to pay off the debt much sooner and save you in interest.
To pay $20,000 in debt in 6 months you would need to make payments towards the debt of at least $3,500.00 per month to cover the debt and any possible interest that may have been charged over the course of the debt.
If you can afford to pay the $3,500.00 per month towards the $20,000.00 debt and get it paid off that quick that is a good option but for some people it may take 5 to 10 years to pay off the $20,000.00 depending on income.
Making extra payments when possible or taking out a side job to make additional income can help you pay back the debt sooner and save you in interest and help to increase your credit score.
When possible make more than the minimum payment on the debt which helps you pay it back quickly and you pay less interest that way as well.
Early payoff of loans can save you hundreds or thousands of dollars in interest over the life of the loan although you should check for any possible prepayment penalties first before paying the loan off early.
However interest can also add up over that time so you may not be able to pay all that back as new interest charges will be added in most cases.
So if you could pay more towards the debt if possible you could pay it off sooner.
If you have credit card debt then you should pay more than the minimum payment and ideally pay off what you borrowed on the credit card the next month in full.
This keeps interests from adding up and increasing your debt on the credit card.
Same with a loan, the longer you have a loan out the more interest that will be charged which makes it harder to pay off that loan.
Only borrow what you reasonably can afford and be able to pay back.