Lan Lan bought 4 gel pens and 2 fountain pens, and Ding Ding bought 16 gel pens, and they both spent the same amount of money. The price of a pen is equal to the price of gel pens.
兰兰买了4枝中性笔和2枝钢笔，丁丁买了16枝这种中性笔，两人用去的钱同样多．一枝钢笔的价钱等于多少枝中性笔的价钱．
<gadget id="calculator">16 - 4</gadget>
<output>12</output>

<gadget id="calculator">12 / 2</gadget>
<output>6</output>

<result>6</result>