A box of 3 pens costs 22.5 yuan, a box of 5 gel pens costs 14 yuan, how much is the unit price of the pen more expensive than the unit price of the gel pen?
一盒钢笔共3支，售价22.5元，一盒中性笔共5支，售价14元，钢笔的单价比中性笔的单价贵多少元．
<gadget id="calculator">22.5 / 3</gadget>
<output>7.5</output>

<gadget id="calculator">14 / 5</gadget>
<output>14/5 = around 2.8</output>

<gadget id="calculator">7.5 - (14/5)</gadget>
<output>4.7</output>

<result>4.7</result>