Stationery store, bookstore and toy store are located in an east-west street in turn. The stationery store is 20 meters west of the bookstore, and the toy store is east of the bookstore 100.

Analysis: According to the meaning of the question, the bookstore can be regarded as the origin, the stationery store is 20 meters west of the bookstore, that is, -20 meters, and the toy store is located east of the bookstore 100 meters, that is,+100 meters. Just solve it.

According to the meaning of the question, the stationery store is 20 meters west of the bookstore and the toy store is 100 meters east of the bookstore.

When the bookstore is the origin, the toy store 100 meters and the stationery store -20 meters.

Xiaoming's positioning is: 40-60=-20,

∴ Xiaoming's position is: -20 meters

Xiaoming's position is in a stationery store.

So the answer is a.