Currency depreciation is the opposite of currency appreciation, which refers to the decrease in the value or real wroth represented by the currency. It is shown in two aspects: one is the decline in the domestic purchasing power of the currency, and the other is the decline in the price of the domestic currency against the foreign currency (foreign exchange rate).
According to the above definition, which of the following description belongs to the depreciation of RMB?
100 yuan can buy 10 kilograms of rice last year, and 15 this year.