The original price of a pen is 18 yuan, but now it is sold at half price. Teacher Zhang brings 108 yuan, how many pens can he buy.
一支钢笔原价18元，现在按半价销售，张老师带108元，可以买多少支钢笔．
<gadget id="calculator">18 / 2</gadget>
<output>9</output>

<gadget id="calculator">108 / 9</gadget>
<output>12</output>

<result>12</result>