A book has 320 pages, and Xiao Ming has 50 pages left after reading it for 9 days. How many pages does Xiao Ming read on average every day?
一本书320页，小明看了9天后还剩下50页．小明平均每天看多少页？
<gadget id="calculator">320 - 50</gadget>
<output>270</output>

<gadget id="calculator">270 / 9</gadget>
<output>30</output>

<result>30</result>