Who Am I?

[luthien-elvenprincess]

I am stuck...here is what I have so far.

Eomer said he lost 15 men and 12 horses in the battle with the orcs beside Fangorn forest. This loss totals 78 legs. Seven hundred and twenty minus 78 equals the 642 legs that Estanesse said left the battleground victorious.
I can't figure out the 720 exactly though...Legalas sees 105 riders of Rohan coming in the distance and it is mentioned that there are 3 horseless riders (which matches perfectly with the fact of 15 men and 12 horses lost in battle). But 105 riders and 3 riderless horses equals 702 legs instead of 720. Possible typo, Estanesse??? I am at a loss to account for the extra 18 legs.

I have spun the rest of the riddle in so many ways trying to figure it out...I am dizzy. Another hint, please!

I am also thinking that one of the songs about the Rangers said something about 'The lost who knows the way'. But, I can't find it. Does this sound familiar to anyone???