Balancing using Half reaction method

This question is asking how to balance the following formula using the half-reaction method.

KMnO4(aq) + H2SO4(aq) + H2O2(l) ---> MnSO4(aq) + K2SO4(aq) + H2O(l) + O2(g)

the answer I got using normal method was;

2KMnO4(aq) + 3H2SO4(aq) + H2O2(l) ---> 2MnSO4(aq) + K2SO4(aq) + 4H2O(l) + 3O2(g)

However my answer and the other guys answers are different, why is this.
Can someone also please explain how to balance this equation using the half-reaction method as I am unaware of this method (as i am studying iGCSE - but I am interested in chem so am eager to learn new things!)