Li Hua bought a watercolor pen, paid 100 yuan, and got back 12.5 yuan. How much is the watercolor pen? (column equation solution)
李华买水彩笔，付出100元，找回12.5元，水彩笔多少元？(列方程解答)
<gadget id="calculator">100 - 12.5</gadget>
<output>87.5</output>

<result>87.5</result>