Most lenders will lend up to 85% loan-to-value on an equity loan/line... for example:
$72,000 value x 85% = $61,200 - $42,000 owed = $19,200 available equity
However, it will depend on the lender's underwriting criteria as to whether or not you will be approved... they have to consider your debt-to-income, and your credit score.
It is beneficial if the interest rate & costs associated with the equity loan/line are less than what you are currently paying in interest on your credit cards... Also, it is vital that you do not rack up credit card balances after you pay them off with the equity loan/line... Most people fall back into the credit card trap after getting out!