In recent years, more and more HK people have gone to Shenzhen to shop on weekends. It has been reported that the prices of goods are lower in Shenzhen.
a) The sales revenue of retailers in the northern New Territories, such as Sheung Shui and Fanling, has greatly decreased over the same period. The prices of goods sold are keept fixed.
i) Explain with the aid of a diagram why this has happened.