Plant one tree every 3 meters on both sides of a 30-meter-long path, and plant both ends. How many saplings should be prepared in total.
在一条长30米的小路两旁每隔3米植一棵，首尾都要植，一共要准备多少棵树苗．
<gadget id="calculator">30 / 3</gadget>
<output>10</output>

<gadget id="calculator">10 + 1</gadget>
<output>11</output>

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

<result>22</result>