A sign in an elevator says the elevator can lift up to 450 kilograms. John has 10 boxes that weigh 13.75 kilograms each, and a number of additional boxes that weigh 15.5 kilograms each. If he puts the 10 boxes on the elevator, how many of the additional boxes can be lifted in the same load?

Answer: the number of additional boxes that can be lifted in the same load is 20

Step-by-step explanation:

Let x represent the number of additional boxes that can be lifted in the same load.

John has 10 boxes that weigh 13.75 kilograms each, and a number of additional boxes that weigh 15.5 kilograms each. If he puts the 10 boxes on the elevator, it means that the total weight if he adds x additional boxes would be

13.75 * 10 + 15.5x

= 137.5 + 15.5x

Since the sign in the elevator says the elevator can lift up to 450 kilograms, it means that

137.5 + 15.5x = 450

15.5x = 450 - 137.5

15.5x = 312.5

x = 312.5/15.5

x = 20.16