In his will, Farmer Fox left his herd of cows to his four daughters as follows: The oldest got half of them, the next got 1/4, the third got 1/5, and the youngest got the remaining 7 cows. How many cows were in the herd?
The three oldest daughters got 1/2 + 1/4 + 1/5 = 19/20 of the herd, so the youngest daughter’s share of 7 cows was 1/20 of the herd. There must have been 140 cows in the herd.