Question 963127
A girl can rake the entire yard in 8 hours.
In 1 hour she can rake 1/8th of the yard.
When a boy does it alone, it takes him 9 hours.
In 1 hour he can rake 1/9th of the yard.
When they work together in 1 hour they can rake (1/8+1/9) of the yard.
In 1 hour they can rake 17/72 of the yard.
Total time taken=72/17hours=254 minutes(approx.)