The original puzzle
A frog is at the bottom of a well 30 feet deep. At each jump, it goes up 3 feet but slides back down 2 feet. How many jumps must it take to come out of the well ?

The Solution
This is an easy one. One must just be careful of the end.
         1. After each complete jump, the frog has gained 1 foot of altitude, 3 up and 2 down.
         2. After 27 complete jumps, the frog has gained 27 feet of altitude.
         3. One more jump and it is out, no sliding back down.