Question

Express the given quantity in terms of the indicated variable.

The concentration (in oz/gal) of salt in a mixture of 3 gal of brine containing 25 oz of salt to which some pure water has been added; x = volume of pure water added (in gal).

Short answer

The concentration is$\frac{25}{3+x}$ gallons.

Step-by-step solution

Step 1. Concept used.

Units of the concentration is

$\text{Concentration}=\frac{\text{Totalouncesofthemineral}}{\text{Totalgallons}}$

Step 2. Given condition.

Write each amount given:

The original number of gallons = 3

Amount of gallons added = x

Total ounces of the mineral = 25

Step 3. Plug the values.

Add the original and added amount of gallons. Then use the formula to find the concentration $\text{Concentration}=\frac{25}{3+x}$.