A manufacturer has 460 litres of a 9% acid solution. How many litres of a 3% acid solution must be added to it so that the acid content in the resulting mixture be more than 5% but less than 7%?

Explanation

To solve the problem step by step, we need to determine how many liters of a 3% acid solution must be added to a 460 liters of a 9% acid solution so that the resulting mixture has an acid content greater than 5% but less than 7%.

### Step 1: Define Variables
Let \( x \) be the number of liters of the 3% acid solution added.

### Step 2: Calculate the Acid Content in the Original Solution
The acid content in the original 460 liters of a 9% solution is calculated as follows:
\[
...