Hari Ram’s present age is three times his son’s present age and two fifth of his father’s present age. The average of the present age of all of them is 46 years. What is the difference between Hari Ram’s son’s present age and Hari Ram’s father’s present age?

Let Hari Ram's present age = x

Then, his son's age = x/3

Father's age = 5x/2

$\frac{x + \frac{x}{3} + \frac{5}{2}x}{3} = 46=> x = 36 \mathrm{yrs}$

Now the required difference =  $\frac{5}{2}x36 - \frac{36}{3} = 78 \mathrm{yrs}$