In a cleaning mixture, the amount of water is directly proportional to the amount of ammonia. A mix with 5 gallons of water requires 10 teaspoons of ammonia. How many gallons of water are needed for 25 teaspoons of ammonia? Write your answer in decimal form.
According to the given proportion, 5 gallons of water correspond to 10 teaspoons of ammonia.
Let x be the number of gallons of water needed for 25 teaspoons of ammonia.
Using the proportionality:
5/10 = x/25
Solving for x:
10x = 125
x = 125/10
x = 12.5
Therefore, 12.5 gallons of water are needed for 25 teaspoons of ammonia.