The mass of hydrogen peroxide dissolved is
It is of the utmost importance - and I can't stress this enough - to always check to see if your chemical equation is balanced. In your case, the form written in the question is clearly not balanced, The balanced chemical equation looks like this
The net ionic equation will give you a better idea of what's going on in this reaction
Basically, you're using potassium permanganate to oxidize hydrogen peroxide to oxygen gas in an acidified solution (that's what the sulfuric acid is for).
You should treat this problem like you would any other titration calculation- figure out how many moles of added potassium permanganate are needed to completely oxidize the hydrogen peroxide.
Of course, go about doing this by using the mole ratio that exists between potassium permanganate and hydrogen peroxide - 2 moles of the former will react with 5 moles of the latter.
So, the number of moles of
This means that the number of moles you had in your hydrogen peroxide solution was
Now use hydrogen peroxide's molar mass to determine how many grams of hydrogen peroxide you would have needed to prepare your solution