1.875 quarts of pure pineapple juice should Theo add to a 20% pineapple drink.
Explanation
Suppose, [tex]x[/tex] quarts of pure pineapple juice should be added with 20% pineapple drink.
As the amount of the mixture is 5 quarts, so the amount of 20% pineapple drink will be: [tex](5-x) quarts[/tex]
Percentage of juice in the pure pineapple juice is 100% and in the mixture is 50%
So, the equation will be.....
[tex]1.00(x)+0.20(5-x)=0.50(5)\\ \\ 1.00x+1-0.20x=2.50\\ \\ 0.80x=2.50-1\\ \\ 0.80x= 1.50\\ \\ x=\frac{1.50}{0.80}=1.875[/tex]
So, 1.875 quarts of pure pineapple juice should Theo add to a 20% pineapple drink.