Plant trees beside a rectangular pond with a length of 20 meters and a width of 12 meters, and plant one tree every 4 meters. How many trees can be planted in total?
在一个长20米，宽12米的长方形池塘边栽树，每4米栽一棵，一共能栽多少棵？
<gadget id="calculator">20 * 2</gadget>
<output>40</output>

<gadget id="calculator">12 * 2</gadget>
<output>24</output>

<gadget id="calculator">40 + 24</gadget>
<output>64</output>

<gadget id="calculator">64 / 4</gadget>
<output>16</output>

<result>16</result>