Chengdong Primary School plans to plant trees on both sides of a 100-meter-long runway, and carry a tree every 5 meters from the beginning to the end. How many trees will be carried in total?
城东小学准备在一条长100米的跑道两边栽树，从头到尾每隔5米载1棵树，一共要载多少棵树？
<gadget id="calculator">100 / 5</gadget>
<output>20</output>

<gadget id="calculator">20 + 1</gadget>
<output>21</output>

<gadget id="calculator">21 * 2</gadget>
<output>42</output>

<result>42</result>