Xiaohong and Xiaodong each put out an equal amount of money to buy exercise books. After buying them, Xiaohong took 4 more books than Xiaodong, so Xiaohong returned 80 cents to Xiaodong. How much is the price of each exercise book.
小红、小冬二个同学各拿出相等的钱去买练习本，买来后，小红比小冬多拿了4本，因此小红还给小冬8角钱．每本练习本的价钱是多少角．
<gadget id="calculator">4 * 2</gadget>
<output>8</output>

<gadget id="calculator">8 / 8</gadget>
<output>1</output>

<result>1</result>