( 1)

Suppose the unit price of A is X, and the purchase price of B is Y.

Then x+y=4400.

x+500+2*[(4/3)y-200]=8500

X=2000，y=2400。

(2) Set up subsidies of A yuan and B yuan respectively.

Then a+b=920

b=2a+80

The solution is a = 280 and b = 640.

∴ A pays 2000+500-280=2200 yuan.

B pay 2000+500+ 3000-640=4860 yuan.