It took Shanshan 4 weeks to write a copybook, a total of 560 characters, how many characters does he write every day on average.
珊珊用4个星期把一本习字本写完，一共560个字，他平均每天写多少个字．
<gadget id="calculator">4 * 7</gadget>
<output>28</output>

<gadget id="calculator">560 / 28</gadget>
<output>20</output>

<result>20</result>