if you don't know the rules of Risk:
The attacker throws 3 dice and the defender throws 2. They compare their strongest dice, and the loser loses a troop. Then they compare their second strongest dice and the loser loses a troop. The defender always wins ties. They do it over and over until until someone runs out of troops.
if they each have infinite troop, how many will they each lose? or what is the ratio of lost troops of one against the other?