The size of shoes is usually in "yard" or "centimeter", and the conversion relationship between them is: y=2x-10. (y indicates the size of the shoe, x indicates the length of the foot in centimeters), dad's foot is 26 cm long, what size shoes should be worn.
鞋的尺码通常用"码"或"厘米"作单位，它们之间的换算关系是：y=2x-10．(y表示鞋的码数，x表示脚长厘米数)，爸爸的脚长26厘米，应穿多少码的鞋．
<gadget id="calculator">2 * 26</gadget>
<output>52</output>

<gadget id="calculator">52 - 10</gadget>
<output>42</output>

<result>42</result>