The price of a fountain pen is 12.8 yuan, which is 6.2 yuan more expensive than a ballpoint pen. How much is the price of a ballpoint pen? (solution by equation)
一支钢笔的价钱是12.8元，比一支圆珠笔贵6.2元．一支圆珠笔的价钱是多少元？(用方程解)
<gadget id="calculator">12.8 - 6.2</gadget>
<output>6.6</output>

<result>6.6</result>