Answer: He should add 8 gallons of water to make 5% bleach solution.
Step-by-step explanation:
Let the number of gallons of water he should add be 'x'.
Since we have given that
Total number of gallon we have = 8
It has 10% beach solution i.e. [tex]\frac{10}{100}\times 8=0.8\ gallon[/tex]
We need to make it a 5% bleach solution by adding water to it.
so, our equation becomes,
[tex]\frac{Bleach}{Total}=\frac{0.8}{8+x}=\frac{5}{100}\\\\\frac{0.8}{8+x}=\frac{1}{20}\\\\20\times 0.8=8+x\\\\16=8+x\\\\x=16-8\\\\x=8\ gallons[/tex]
Hence, he should add 8 gallons of water to make 5% bleach solution.
