Impossible problem? Test your brain power!

This is the problem

Suppose you spent a total of 16480 Neopoints on four different codestones that you found on the Shop Wizard. The Mau Codestone's cost was equal to the Tai-Kai Codestone plus half the cost of the Main Codestone. The Tai-Kai Codestone's cost was the same as the Eo Codestone minus the cost of the Main Codestone. You paid three times as much for the Mau Codestone as you did for the Main codestone. The Eo Codestone cost as much as the Tai-Kai and the Main Codestones put together.

How much did the Eo Codestone cost? Round to the nearest whole number



Mau = Tai + 1/2main
Tai = Eo - Main
3main = Mau
Eo = Tai + Main
All together = 16480


Main = x
Mau = y
Tai = a
Eo = b


Y = a + 1/2x
A = b - x
3x = y
B = a + x
X + Y + A + B = 16480

so b = ??????

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