Xiao Ming buys a stamp album and two diaries for 8.4 yuan, and a stamp album for 4.8 yuan. How much is the price of a diary?
小明买一本集邮册和两本日记本共用去8.4元，一本集邮册4.8元，一本日记本的价钱是多少？
<gadget id="calculator">8.4 - 4.8</gadget>
<output>3.6</output>

<gadget id="calculator">3.6 / 2</gadget>
<output>1.8</output>

<result>1.8</result>