1. The cooling system of Alex's car holds 10 quarts. It is now filled with a mixture that is 60% water and 40% antifreeze. Hearing a weather forecast for severe cold, Alex decides to increase the strenth of the antifreeze mixture to 50%. To do this, Alex must drain off a certain number of quarts from the cooling system and then replace them by pure antifreeze. How many quarts must be drained?

0.6w + 0.4a = 0.5 ? I know 6 quart will be water and 4 quart antifreeze so if I drain one quart I will have 5.4 water and 3.6 antifreeze then I can add 1 antifreeze to make 5.4 w and 4.6 antifreeze. I know I have to do this until I make 5 water and 5 antifreeze. I tried to set up an equation to make it easier but I can't do it. 2.Taylor works after school in a health food store, where one of the more challenging tasks is to add cranberry juice to apple juice to make a cranapple drink. A liter of apple juice costs $0.80 and a liter of cranberry juice costs $1.25. The mixture is to be sold for exactly the cost of the ingredients, at $1.09 per liter. How many liters of each juice should Taylor use to make 20 liters of the cranapple mixture? 0.8A + 1.25c = 21.80 Am I supposed to guess and check from here? I tried 10 liters each and it is 8 + 12.50 = 20.50 Can someone show me a better way to do this?
Vicky.

I really appreciate the help I get!!!