Value Mixture problem

Question

How much water must be evaporated from 16 qt of a 55% antifreeze solution to produce an 80% solution?

Answer 1

Convert to measures of water:

0.45(16) - w = 0.2(16 - w)

7.2 - w = 3.2 - 0.2w

4 = 0.8w

5 = w

Answer 2

16(.55)=8.8 is the amount of antifreeze in the original solution. 

 

Then take 8.8/.8 = 11 which is the total amount of solution to make it 80%. So 16-11=5 water that must be evaporated.