A road is 30 meters long, and trees are to be planted on both sides of the road, every 5 meters, and trees are to be planted at the beginning and end, how many trees are needed?
一条马路长30米，要在马路的两边栽树，每隔5米栽一棵，在开头和末尾处都要栽上树，需要多少棵树？
<gadget id="calculator">30 / 2</gadget>
<output>15</output>

<gadget id="calculator">15 + 1</gadget>
<output>16</output>

<gadget id="calculator">16 * 2</gadget>
<output>32</output>

<result>32</result>