Answer: 1620 gallons of water
Explanation:
Let the water that is in the tank when the tank is at full capacity be represented by x.
Therefore, 40% of x = 648
40% × x = 648
40/100 × x = 648
0.4 × x = 648
0.4x = 648
x = 648/0.4
x = 1620
The answer is 1620 gallons