Xiao Ming went to the store and bought several fountain pens and ballpoint pens. The average price of each pen was 6 yuan. It is known that the price of a fountain pen is half that of a ballpoint pen, and Xiao Ming buys half as many ballpoint pens as the number of fountain pens, so how much is the price of each pen.
小明到商店买了若干支钢笔与圆珠笔，平均每支笔价钱是6元．已知钢笔价钱比圆珠笔贵一半，小明购买圆珠笔的支数比钢笔的支数多一半，那么钢笔每支售价是多少元．
<gadget id="calculator">15 / 2</gadget>
<output>15/2 = around 7.5</output>

<result>15/2 = around 7.5</result>