Buying 8 notebooks and 4 ballpoint pens costs 26 yuan. It is known that the unit price of the notebook is 1.8 yuan. How much is the unit price of the ballpoint pen?
买8本笔记本和4枝圆珠笔共用去26元，已知笔记本的单价是1.8元，圆珠笔的单价是多少元？
<gadget id="calculator">1.8 * 8</gadget>
<output>14.4</output>

<gadget id="calculator">26 - 14.4</gadget>
<output>11.6</output>

<gadget id="calculator">11.6 / 4</gadget>
<output>2.9</output>

<result>2.9</result>