Walnuts are sold in Shanxi specialty stores, and the purchase price is 40 yuan per kilogram, which is sold in 60 yuan per kilogram, and the average daily sales can be100kg.

Solution: (1) Solution: Suppose that the price per kilogram of walnuts should be reduced by X yuan ...1min.

According to the meaning of the question, get (60-x-40) (100+x/2× 20) = 2240 ... 4 points.

Simplify, get x2﹣ 10x+24=0, get x 1=4, x2 = 6 ... 6 points.

A: The price per kilogram of walnuts should be reduced by 4 yuan or 6 yuan ... 7 points.

(2) Solution: According to (1), the price per kilogram of walnuts can be reduced in 4 yuan or 6 yuan.

Because it is necessary to benefit customers as much as possible, the price per kilogram of walnuts should be reduced by 6 yuan ... 8 points.

At this time, the selling price is: 60 ~ 6 = 54 yuan, ... 9 cents.

Answer: The store should sell at 10% off the original selling price ...10 points.