A chemist needs to create a 50% HCl solution. (HCl is hydrochloric acid. A "50% HCl solution" contains 50% HCl and the other 50% is water.)

How much of a 70% HCl solution must be mixed with 30 ml of a 25% HCl solution in order to result in a 50% HCl solution?

Round your answer to 2 places after the decimal point (if necessary) and do NOT type any units (such as "ml") in the answer box.