Question

It takes a groundskeeper 40 minutes to prepare a little league baseball field for a game. it takes his assistant 50 minutes to prepare the same field. how long will it take if they work together to prepare the field

Answer 1

1/40+1/50=1/n
5/200+4/200=1/n
9/200=1/n
9n=200
n=200/9 minutes for both of them to prepare the field
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