Monu's father is $26$ years younger than Monu's grandfather and $29$ years older than Monu. The sum of the ages of all the three is $135$ years. What is the age of each one of them?

A man is $10$ times older than his grandson. He is also $54$ years older than him. Find their present ages.

The difference between the ages of two cousins is $10$ years. $15$ years ago, if the elder one was twice as old as the younger one, find their present ages.

Half of a herd of deer are grazing in the field and three - fourths of the remaining are playing nearby. The rest $9$ are drinking water from the pond. Find the number of deer in the herd.