Obviously, I plan to buy some pens for my class and donate them to Project Hope. A stationery store advertises that buying more than two (including two) goods in our store is the original price.

1+ 12(x- 1)= 23x，

12x+ 12=23x，

16x= 12，

x=3，

Therefore, when buying 3 pieces, it is equally cheap in A stationery store and B stationery store; Less than 3 yuan, cheap in B stationery store; More than 3 yuan, the stationery store is cheaper,

A: 3 pieces are the same; If there are less than 3 pieces, store B is cost-effective; If there are more than three pieces, Store A will get a good deal.