How much of the mowing could be done in 1 hour using all 3 machines? Math Question?

Question

A lawn mower can cut the park lawn in 10 hours. A different mower can cut the same lawn in 12 hours, and a third type can cut it in 15 hours.

How do you solve this?
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Thank you

Answer 1

Mower one: 1/10 of park in one hour.
Mower two: 1/12 of park in one hour.
Mower three: 1/15 of park in one hour.

Total in one hour with all three mowers:

1/10 + 1/12 + 1/15 = total Change to 60ths
6/60 + 5/60 + 4/60 = 15/60 = 1/4 of the park in an hour

Answer 2

(x/10 + x/12 + x/15 = 1) x 60
6x + 5x + 4x = 60
15x = 60
x = 4 hours --> time it takes to mow the whole lawn
therefore, 1/4 of the mowing could be done in 1 hour.

Answer 3

answer is 1/4.
1/10+1/12+1/15=15/60 (work done by all three in 1 hour)