Pooja, Shipra and Mounika are three sisters .Pooja and Shipra are twins. The ratio of sum of the ages of Pooja and Shipra is same as that of Mounika alone. Three years earlier the ratio of age of Pooja and Mounika was 2:7 . what will be the age of Shipra 3 years hence?

Since Pooja and Shipra are twins so their ages be same. Let their ages be x and age of Mounika be y , then 

           x+x = y    -------(1) 

 and    $\frac{x-3}{y-3}=\frac{2}{7}\Rightarrow 7x-2y=15$ 

Now, from  equation (1), 

         7x - 4x = 15  =>  x = 5

So the age of Shipra 3 years hence will be 5+3 = 8 years