Help me... I'm in 2nd year of the High School... i need help with this +REP
I've used Google translator in it.. because i'm brazilian so it was in portuguese

1)When an atom of the isotope 228 thorium releases an alpha particle becomes a radio atom, according to the equation:
Th z=228 and a=x ~> Ra z=y a=88
Detemine x and y:

Help me :s