Given that the tank is 1/3 full of water, and that it requires 16 gallons to fill. 1 full tank -1/3 tank = 2/3 of the tank is empty, which is equal to 16 gallons.
If 2/3 of the tank equals 16 gallons, this means 1/3 of the tank is equal to 16 / 2 gallons = 8 gallons
The total capacity of the tank or how much the tanks holds = 16 + 8 = <<16+8=24>>24 gallons
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