As an employee of a summer sports camp, one of your jobs is to prepare the tank of vitamin water for use throughout the day. the mixture calls for 75% pure water and 25% concentrated vitamin drink. how many gallons of water should you add to 16 gallons of concentrated vitamin drink?

Given: 
Mixture of vitamin water = 75% pure water & 25% concentrated vitamin drink.  
To find:  
Quantity of water to be added to 16 gallons of concentrated vitamin drink to prepare a tank of vitamin water.  
Solution: 
Let total amount of mixture be x. 
25% of x = 16 gallons (from given information)  
When 25% of x is 16 gallons, the remaining 75% of x will be calculated as below:
 (16/25)*75 = 48 
  75% of x = 48 gallons. This means 48 gallons pure water is required to be added to mixture to prepare a tank of vitamin water.

The answer to this is the 3rd choice!