Answer:
10.8 gallons
Step-by-step explanation:
First change everything to inches:
2.75 ft = 33 in
1.5 ft = 18 in
Volume of tank = lwh = (33)(18)(7) = 4158 in³
The tank is 40% full, so only 60% is need to fill it. To find 60%, multiply 4158 by 0.6 = 2494.8 in³
Now find out how much 2494.8 in³ is in gallons:
231 in³ = 1 gallon
1 in³ = 1/231 gallons
2494.8 = (1/231)(2494.8) gallons = 10.8 gallons
