In this case, we'll have to carry out several steps to find the solution. 
Step 01:
Data:
pyramid side: 
h = 3.25 ft
b = 2.5 ft
square base: 
s = 2.5 ft
gallon of gold paint: 
400 ft² 
Step 02:
surface area: 
square base area: 
A = s² = (2.5 ft)² = 6.25 ft² 
total pyramid sides area: 
A = (b * h) / 2 
A = (2.5 ft * 3.25 ft) / 2 = 4.0625 ft² 
total pyramid sides area = 4 * 4.0625 ft² = 16.25 ft² 
total trophy area: 
total trophy area = 6.25 ft² + 16.25 ft² = 22.5 ft² 
maximum number of trophies: 
maximum number of trophies = 400 ft² / 22.5 ft² = 17.78 
The answer is: 
square base area = 6.25 ft² 
pyramid side area = 4.0625 ft² 
total pyramid sides area = 16.25 ft²
total trophy area = 22.5 ft² 
maximum number of trophies = 17