You know that: g+s+w=62000
You also know that: s=2g
Substitute that in: g+2g+w=62000
So what you get is: g+2g+3g+2000=62000
Change things around: 6g=60000
divide by 6: g=10000
remember that g means the grandchildren put together, separately they get 5000 each.
Can you figure out the rest?