$10$ years ago,Mohan was thrice as old as Ram was,but $10$ years hence,he will be only twice as old as Ram. Find Mohan's present age (in years).

The ratio between the present ages of $P$ and $Q$ is $6:7$. If $Q$ is $4 \text{ years}$ older than $P$,what will be the ratio of the ages of $P$ and $Q$ after $4 \text{ years}$?

The ratio between the school ages of Neelam and Shaan is $5:6$. If the ratio between one-third of Neelam's age and half of Shaan's age is $5:9$,then what is the school age of Shaan (in years)?

The age of the father is $30 \text{ years}$ more than the son's age. Ten $\text{years}$ hence,the father's age will become three times the son's age at that time. What is the son's present age in $\text{years}$?

Radha's present age is three years less than twice her age $12$ years ago. Also,the ratio between Raj's present age and Radha's present age is $4:9$. What will be Raj's age after $5$ years? (in years)

Shan is $55$ years old. Sathian is $5$ years junior to Shan and $6$ years senior to Balan. The youngest brother of Balan is Devan,and he is $7$ years junior to him. What is the age difference between Devan and Shan (in years)?