THE INHERITANCE PROBLEM

A man divides his cattle among his four sons so that the oldest son gets 1/2 the herd, the next son 1/4, the next 1/5, and the youngest son the remaining 20 cows. How many cattle are in the herd?

SOLUTION

The man has 400 cattle in his herd. 

(Trial and error, a little fraction work, or simple algebra will yield the solution.)