Answer: 73.4 gallons
Explanation: We know that the tank has 2.5 feet across on the inside, so the diameter is 2.5 feet, this means that the radius us 1.25 ft (because diameter = 2*radius)
Now, the volume of fluid inside the tank is:
V = pi*radius^2*height
Where pi = 3.14
radius = 1.25ft
height = 2ft
V = 1.25^2*2*3.14 = 9.81 ft^2
Now, for each ft^2 we have 7.48 gallons, so we have:
9.81*7.48 = 73.4 gallons of oil