Who is asking: Student
WORKING TOGETHER ON A JOB: Patrice, by himself can paint 4 rooms in 10 hours. If he hires April to help they can do the same job together in 6 hours. If he lets April work alone , how long will it take her to paint 4 rooms?
What you need to do is to see how many rooms Patrice alone and Patrice and April can paint in the same number of hours.
(I chose 30 hours since 30 is the least common multiple of 10 and 6.)
- In 10 hours Patrice can paint 4 rooms so in 30 hours he can paint 3x4 = 12 rooms.
- In 6 hours Patrice and April together can paint 4 rooms so in 30 hours they can paint 5x4 = 20 rooms.
This means that in 30 hours, April can paint 8 rooms and hence
it would take her 15 hours to paint 4 rooms.