Answer:
2) 12,000 ft²
3) 30 gallons.
Explanation:
2) 1. You can calculate the lateral surface area of the exterior walls of the warehouse by applying the formula shown below:

Where h is the height, l is the lenght and w is the width.
2. Substitute values and you obtain that the lateral area is:

3) You know that 1 gallon of paint covers 400 ft², therefore for 12,000 ft² are needed the following number of gallons (which is represented by x):