Mr. Li paid 350 yuan for the ink and pen. Among them, there are 16 bottles of ink, each bottle is 5 yuan, and the remaining money is used to buy 18 pens. How much is each pen?
李老师购买墨水和钢笔，共付了350元．其中墨水16瓶，每瓶5元，剩下的钱买了18支钢笔，每支钢笔多少元？
<gadget id="calculator">16 * 5</gadget>
<output>80</output>

<gadget id="calculator">350 - 80</gadget>
<output>270</output>

<gadget id="calculator">270 / 18</gadget>
<output>15</output>

<result>15</result>