So, we're told that for every gallon of water in the swimming pool there should be four grams of chlorine. In the most simple terms, it's simply we should have a ratio 4grams chlorine:1 gallon of water. We can solve it like any other proportion question as a result, giving us:
[tex] \frac{4\text{ grams}}{1\text{ gallon}}=\frac{x \text{ grams}}{13\text{ gallons}}
[/tex]
To solve this we want to multiply both sides by 13 gallons to get rid of the gallons and also to isolate the x, so:
[tex] \frac{4\text{ grams}}{1 \text{ gallon}}*13 \text{ gallons} = x\text{ grams} \implies\\
42\text{ grams}=x\text{ grams} [/tex]
Which means we should add 42 grams of chlorine in a pool containing 13 gallons of watter.
