The black fountain pens in a store are 1.1 yuan each, and the blue fountain pens are 1.9 yuan each. A total of 26 of the two kinds of fountain pens are bought, and the cost is 35 yuan. How many black fountain pens did you buy?
某商店的黑色水笔每支1.1元，蓝色水笔每支1.9元，两种水笔共买了26支，花了35元，则黑色水笔买了多少支．
<gadget id="calculator">26 * 1.9</gadget>
<output>49.4</output>

<gadget id="calculator">49.4 - 35</gadget>
<output>14.4</output>

<gadget id="calculator">1.9 - 1.1</gadget>
<output>0.8</output>

<gadget id="calculator">14.4 / 0.8</gadget>
<output>18</output>

<result>18</result>