Together

Grandfather, father, and son are carpenters. They decided to make a wardrobe.
Father produces it for 12 hours, his son for 15 hours, and grandfather for 10 hours.
How long will they make it together?

Correct result:

x =  4 h

Solution:

x•(1/12+1/15+1/10)=1

15x = 60

x = 4

Our simple equation calculator calculates it.

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