A pair of shoes costs 45, two pairs of 90; The customer 100 yuan gave the neighbor change, and Miss Wang received 100 yuan change, and then gave the neighbor 100 yuan real money, even with the neighbor;

60 yuan sold the shoes to the customers, and after giving them to the customers, he bought 40 yuan with his own money, which is equivalent to the customers taking two pairs of shoes for nothing (at the expense of 90 yuan), and 40 yuan took the money.