Awater tank is currently three-quarters full. if 2500 gallons are drained, the tank will be one-third full. how many gallons of water can the tank hold when full?

We know from question that:

3/4 * volume - 1/3 * volume = 2500

Solving this equation for volume gives:

Volume * ( 3/4 - 1/3 ) = 2500

Volume * ( 9/12 - 4/12) = 2500

Volume * 5/12 = 2500

Volume = 2500 / ( 5/12)

Volume = 2500 * 12 / 5 = 500 * 12 = 6000 gallons.

Logical equivalent of the give question is its contrapositive