The price of a ballpoint pen is multiplied by 3 and subtracted 0.5 yuan, which is the same as the price of a fountain pen. The price of a fountain pen is 10 yuan. How much is the price of a ballpoint pen?
一支圆珠笔的价格乘3，再减去0.5元，就和一支钢笔的价格相同，一支钢笔的价格是10元，一支圆珠笔的价格是多少元？
<gadget id="calculator">10 + 0.5</gadget>
<output>10.5</output>

<gadget id="calculator">10.5 / 3</gadget>
<output>3.5</output>

<result>3.5</result>