Plant trees on one side of the 90-meter road (both ends are planted), and plant one tree every 3 meters. How many trees can be planted in total?
在90米的道路一边植树(两端都植)，每隔3米植一棵，一共可以植多少棵树．
<gadget id="calculator">90 / 3</gadget>
<output>30</output>

<gadget id="calculator">30 + 1</gadget>
<output>31</output>

<result>31</result>