The students want to plant trees on both sides of a 280-meter road, and plant one tree every 40 meters. If trees are planted at both ends, how many trees need to be planted?
同学们要给一段280米的公路两边植树，每隔40米栽一棵，如果两端都植树，需要栽多少棵树？
<gadget id="calculator">280 / 40</gadget>
<output>7</output>

<gadget id="calculator">7 + 1</gadget>
<output>8</output>

<gadget id="calculator">8 * 2</gadget>
<output>16</output>

<result>16</result>