To find the depth of the storage unit, we can use the formula for the volume of a rectangular prism, which is given by:
\[ \text{Volume} = \text{Length} \times \text{Width} \times \text{Depth} \]
In this case, the volume of the storage unit is 750 cubic feet, the length is 12 feet, and the width is 9 feet. We need to find the depth.
Rearranging the formula gives us:
\[ \text{Depth} = \frac{\text{Volume}}{\text{Length} \times \text{Width}} \]
Now, substituting in the values:
\[ \text{Depth} = \frac{750 \text{ cubic feet}}{12 \text{ feet} \times 9 \text{ feet}} \]
Calculating the area of the base (length times width):
\[ 12 \text{ feet} \times 9 \text{ feet} = 108 \text{ square feet} \]
Now, substituting back to find the depth:
\[ \text{Depth} = \frac{750}{108} \]
Calculating:
\[ \text{Depth} \approx 6.9444 \text{ feet} \]
Rounding to the nearest whole number, the depth of the storage unit is approximately:
\[ \text{Depth} \approx 7 \text{ feet} \]
Thus, the depth of the storage unit is approximately 7 feet.