The weight of a box varies directly as the volume of the box. If a 138-pound box has a volume of 23 gallons, what is the weight of a box that has a volume of 25 gallons?
Let x be the weight of the box.
Since the weight of a box varies directly as the volume of the box, we can write the equation: x = k * V, where k is the constant of variation and V is the volume of the box.
To find the value of k, we can use the given information that a 138-pound box has a volume of 23 gallons: 138 = k * 23.
Dividing both sides of the equation by 23, we get: k = 138/23 = 6.
Now we can use the value of k to find the weight of a box that has a volume of 25 gallons: x = 6 * 25 = 150 pounds.
Therefore, the weight of a box that has a volume of 25 gallons is 150 pounds. Answer: \boxed{150}.