Zheng Hua bought 2 math homework books and 1 Chinese homework book, which cost 2.5 yuan in total. If each math homework book is a yuan, how much is each Chinese homework book.
郑华买了2个数学作业本和1个语文作业本，共用去2.5元，如果每个数学作业本a元，那么每个语文作业本多少元．
<gadget id="calculator">2.5 - 2</gadget>
<output>0.5</output>

<result>0.5</result>