Antonio is a chemist and needs 15 liters (l) of a 25% hydrochloric acid solution. He discovers he is out of the 25% hydrochloric acid solution. He checks his supply shelf and finds he has a large supply of both 40% and 10% hydrochloric acid solutions. He decides to use the 40% and 10% solutions to make 15 /of a 25% solution. How many liters of the 40% solution and of the 10% solution should he mix?

Write a system of equations that can be used to solve the problem. Then solve the system and deter-mine the answer.