The length of shoes is usually in "centimeter" or "yard", and the conversion relationship between them is a=(1/2)b+5. (a indicates the number of centimeters, b indicates the number of yards) According to this relationship, what is the size of a shoe with a length of 20 centimeters converted into a unit of "yard"
鞋的长度通常用"厘米"或"码"作单位，它们之间的换算关系是a=(1/2)b+5．(a表示厘米数，b表示码数)根据这个关系，长度20厘米的鞋换算成以"码"作单位是多少码
<gadget id="calculator">20 - 5</gadget>
<output>15</output>

<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">15 / (1/2)</gadget>
<output>30</output>

<result>30</result>