depth of the well=30 feet
length the snail ascends during day = 3 feet
length it descends at night = 2 feet
therefore, the equivalent length it covers at the end of the day=(3-2)feet = 1 feet
So, After 27 days it will cover: 27 feet
Then, the next day it will cover : (27+3) feet = 30 feet
Therefore, the snail takes (27+1)days i.e. 28 days to climb out of the well.......
