Method 1:
17 sheep, the eldest son gets 1/2, the second son gets 1/3, and the third son gets 1/9, that is, 17 sheep share1/2:1/. Therefore:
9+6+2= 17
The eldest son gets: 17× 9/ 17 = 9.
Second son: 17× 6/ 17 = 6.
Share of the third son: 17× 2/ 17 = 2.
Solving this problem with equations is equally simple.
Method 2: According to the problem, the boss collected 17/2 cows, the second 17/3 cows and the third 17/9 cows.
Then the second child is 2/3 of the boss and the third child is 2/9 of the boss.
Suppose the boss receives X cows, then the second child receives 2/3x cows and the third child receives 2/9x cows.
x+2/3x+2/9x= 17
x=9
So the boss collected 9 cows, the second one collected 6 cows and the third one collected 2 cows.