Mr. Wang bought some footballs and volleyballs for 800 yuan, 170 yuan for the footballs, and 18 volleyballs for the remaining money. How much is each volleyball?
王老师用了800元买了一些足球和排球，买足球用去了170元，剩下的钱买了18个排球．每个排球多少元？
<gadget id="calculator">800 - 170</gadget>
<output>630</output>

<gadget id="calculator">630 / 18</gadget>
<output>35</output>

<result>35</result>