A got married 6 years ago.  Today her age is \(\frac{5}{4}\) times her age at the time of marriage.  His son's age is \(\frac{1}{10}\) times her age.  The age of her son is?

3

       A                              A

Today's age              Marriage time age

⇒    5              :              4 ...... (diff. 1   = 6 years)

⇒   30             :             24

Son's age = 30 × \(\frac{1}{10}\) = 3 years