The ratio of present ages of a son and his father is 1:5 and that of his mother and his father is 4:5. After 4 years the ratio of age of son to his mother age will be 3:10. Find the present age of father ( in years ) ?

70

                           Son : Father               Mother  :  Father       

 (given)                 1     :    5         &             4   :    5      

  so,                →    Son  :  Father  :  Mother

                      →       1   :     5       :     4

That means          son   :   mother 

                          1       :      4

Let age of son = x  ,  age of mother = 4x  and age of father = 5x 

According to question , after 4 years 

\(\frac{x\;+\;4}{4x\;+4}\)  = \(\frac{3}{10}\)      

10x + 40 = 12x + 12 

2x = 28 

x = 14 

As , age of father = 5x                                            

Age of Father = 14 × 5 =70 years