Xiaoliang wrote 420 brush characters in 4 weeks. How many brush characters does he write on average every day?
小亮用了4个星期写了420个毛笔字．他平均每天写多少个毛笔字？
<gadget id="calculator">420 / 4 / 7</gadget>
<output>15</output>

<result>15</result>