Let's present age of Girish is x years
and present age of Ramesh is y years.
30.5 years ago,
7(x-30.5)+2=y-30.5................(i)
After 2.5 years,
(y+2.5)=2(x-0.5).....................(ii)
simplify (ii), we get
y=2x-3.5.................................(iii)
Now put value of Y from (iii) in to (i)
7(x-30.5)+2=(2x-3.5)-30.5
7x-213.5+2=2x-34
5x=177.5
x=35.5
present age of girish is 35 & 1/2 years
35.5+12.5=48 years
after 12.5 years girish age will be 48 years