In this question there are information's of immense importance and that can go a long way in helping to solve the given question. It is given that one brother eats 3/5 of the cereal and the other brother eats 3/10 of the cereal. The answer that needs to be found is that the amount of cereal the other brother eats more.
The amount of cereal eaten more by the other brother = (3/5) - (3/10)
= ( 6 - 3)/ 10
= 3/10
So the other brother does not eat more, but the first brother has eaten 3/10 more than the other brother.