In order to green the road, the Garden Bureau planted a tree every 4 meters on both sides of a section of the road. A total of 74 trees were planted. Now it is necessary to plant a tree every 6 meters. How many trees need to be planted?
园林局为了绿化公路，在一段公路的两边每隔4米栽一棵树，一共栽树74棵，现在要改成每隔6米栽一棵树．需要栽树多少棵？
<gadget id="calculator">74 / 2</gadget>
<output>37</output>

<gadget id="calculator">37 - 1</gadget>
<output>36</output>

<gadget id="calculator">36 * 4</gadget>
<output>144</output>

<gadget id="calculator">144 / 6</gadget>
<output>24</output>

<gadget id="calculator">24 + 1</gadget>
<output>25</output>

<gadget id="calculator">25 * 2</gadget>
<output>50</output>

<result>50</result>