A red fountain pen is 5 yuan, a blue fountain pen is 7 yuan, and a total of 16 fountain pens are bought for 102 yuan. How many blue fountain pens did you buy?
红色水笔5元一支，蓝色水笔7元一支，花102元共买了16支，蓝色水笔买了多少支．
<gadget id="calculator">16 * 5</gadget>
<output>80</output>

<gadget id="calculator">102 - 80</gadget>
<output>22</output>

<gadget id="calculator">7 - 5</gadget>
<output>2</output>

<gadget id="calculator">22 / 2</gadget>
<output>11</output>

<result>11</result>