Answer:
13 cups of the 80% chlorine solution + 7 cups of the 60% chlorine solution
Explanation:
The pool company recommendation is 20 cups of 73% chlorine to treat their pool
Concentration of chlorine solution in stock = 80% and 60%
Therefore to make 20 cups of 73% solution, we require;
X cups of the 80% chlorine solution and
Y cups of the 60% chlorine solution
That gives 0.8·X + 06·Y = 0.73 × 20
X + Y = 20
Solving gives X = 13 cups
and Y = 7 cups
Therefore to make the optimal solution, 13 cups of the 80% chlorine solution should be mixed with 7 cups of the 60% chlorine solution.