Can't understand this Redox equation! Help!

[eddsjd]

Original-> Na₂Cr₂O₇ + HNO₃ + H₂O₂ = H₃CrO₈ + NaNO₃ + H₂O
Balanced-> Na₂Cr₂O₇ + 2 HNO₃ + 7 H₂O₂ = 2 H₃CrO₈ + 2 NaNO₃ + 5 H₂O
(balanced from the online balancer)

why does the peroxide split 9/2 of its oxygen into H₃CrO₈ and 5/2 into H₂O? i mean, why the 9 and 5? it just seems a little random...