3 boys or 5 girls can clean a compound in 8 hours. in how many hours will 2 boy 2 girls clean the same compound

Answer 1

each boy can do 1/24 the job in an hour
each girl can do 1/40

so, 2boys + 2girls can do 2/24 + 2/40 of the job in an hour

2/24+2/40 = 2/15

so, they can do the job in 15/2 hours