A string is cut in half. One of the halves is thrown away. One fifth of the remaining half is cut away and the piece left is 8 feet long. How long was the string initially? Justify your answer
The string was initially 20 feet long. Four fifths of one half of the string is 8 feet long, so half of the string is 10 feet long. Double 10 and you get 20. Therefore, the string was 20 feet long to begin with.