A farmer died leaving his 17 horses to his three sons.
When his sons opened up the Will it read:

My eldest son should get 1/2 (half) of total horses;
My middle son should be given 1/3rd (one-third) of the total horses;
My youngest son should be given 1/9th (one-ninth) of the total horses.

As it's impossible to divide 17 into half or 17 by 3 or 17 by 9, the
three sons started to fight with each other.

So, they decided to go to a farmer friend whom they considered quite
smart, to see if he could work it out for them.

The farmer friend read the Will patiently, and after giving due thought,
he brought one of his own horses over and added it to the 17. That
increased the total to 18 horses.

Farmer math


Now, he divided the horses according to their father's Will.

Half of 18 = 9. So he gave the eldest son 9 horses.
1/3rd of 18 = 6. So he gave the middle son 6 horses.
1/9th of 18 = 2. So he gave the youngest son 2 horses.

Now add up how many horses they have:

Eldest son 9
Middle son 6
Youngest son 2

TOTAL IS 17

Now this leaves one horse over, so the farmer friend takes his horse back to his farm.
Problem Solved!