Question

Layna can paint a 350-square-foot room in 4 hours. It takes Bebe 7 hours to paint the same room. Which equation can be used to find t, the time it takes Layna and Bebe to paint the room together?

Answer 1

The amount of work done by Layna every hour is 1/4 and that of Bebe is 1/7. These are all dependent on their rates to do the job alone. After working for t hours, they will accomplish 1 job. Thus, this is shown in the equation,
(1/7 + 1/4) x t = 1
Solving for t gives an answer of 2.55 hours.

Answer 2

This problem is a work problem where it involves two people working together to finish something. To solve this we need to think the problem in terms of how much a person can do per unit of time. Layna's job can be represented as 1/4 where it means she can do 1 job per 4 hours. On the other hand, Bebe's job can be represented by 1/7. Together, they can do it in t hours therefore we represent their work together by 1/t. The expression to be used here will be:
1/4 + 1/7 = 1/t