# Rosamaria is setting up a 20-gallon saltwater fish tank that needs to have a salt content of 3.5%. If Rosamaria has water that has 2.5% salt and water that has 3.7% salt, how many gallons of the water with 3.7% salt content should Rosamaria use?

##### 1 Answer

May 24, 2017

#### Explanation:

Your mathematical expression is:

x stands for volume of water required from 2.5% salty water stock. When you get this amount, the rest (20-x) will be taken from 3.7% salty water stock.

Solve this question:

and x is

Take 3.33 gallons from 2.5% salty water stock and take