Solving Algebraic Word Problems:

What are the capacities of two water storage tanks in a nuclear facility if one holds 9 gallons less than three times another, and their whole capacity is 63 gallons?

Solution:

Step 1. Let x = Capacity of the Smaller Tank

Step 2. Then, 3x - 9 = Capacity of the Larger Tank

Step 3. Total Capacity = Capacity of the Smaller Tank + Capacity of the Larger Tank

63 = x + (3x - 9)

Step 4. Solving for x:

x + (3x - 9)      = 63

4x - 9 = 63

4x = 63 + 9

4x = 72

x = 18

Solving for the other unknown:

3x - 9  = 3(18) - 9

3x - 9  = 54 - 9

3x - 9  = 45

Answer:         

Capacity of the Smaller Tank = 18 gallons

Capacity of the Larger Tank = 45 gallons

Step 5. The larger tank holds 9 gallons less than three times the smaller tank.

3(18) - 9 = 54 - 9 = 45

The total capacity of the two tanks is 63 gallons.

18 + 45 = 63

Therefore, the answers check.