Painting the fence 2 solution

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Tere takes 6 hours to paint a fence. Ihaka takes 3 hours to paint the same fence.

How long does it take them to paint the fence together?

Solution:

Find how much of the fence each person can paint in 1 hour.

Tere can paint 1/6 of the fence per hour.
Ihaka can paint 1/3 of the fence per hour.

Together, they can paint 1/3 + 1/6 = 3/6 (or 1/2) of the fence in 1 hour. Therefore it will take them 2 hours to paint the whole fence.