A fountain pen is 3.6 yuan more expensive than a ballpoint pen. The unit price ratio of a ballpoint pen to a fountain pen is 2:5. What is the unit price of a fountain pen?
一支钢笔比一支圆珠笔贵3.6元，圆珠笔与钢笔的单价比是2：5，一只钢笔的单价是多少元．
<gadget id="calculator">5 - 2</gadget>
<output>3</output>

<gadget id="calculator">3.6 / 3</gadget>
<output>1.2</output>

<gadget id="calculator">1.2 * 5</gadget>
<output>6</output>

<result>6</result>