Answer:
20 feet
Explanation:
Let's start by using the formula for the volume of a rectangular box:

where:
- V is the volume
- l is the length
- w is the width
- h is the height
We know that the box is half filled with grain, so the volume of the grain is:

We also know that the volume of the grain is 180 cubic feet, so we can set up an equation:

We are given that the box is 6 feet wide and 3 feet long, so we can substitute those values in:

Simplifying:


Therefore, the depth of the box is 20 feet.