If a tree is planted every 4 meters around a square garden with a side length of 20 meters, how many trees are planted in total?
沿边长为20米的正方形花园四周每隔4米种一棵树，共种树多少棵．
<gadget id="calculator">4 / 4</gadget>
<output>1</output>

<gadget id="calculator">20 * 1</gadget>
<output>20</output>

<result>20</result>