Plant trees in an open space with a length of 30 meters and a width of 20 meters. If the distance between rows and columns is 5 meters, how many trees can be planted at most?
在长30米、宽20米的空地上种树，若规定行距和列距都是5米，则最多可栽多少棵树．
<gadget id="calculator">30 / 5</gadget>
<output>6</output>

<gadget id="calculator">6 + 1</gadget>
<output>7</output>

<gadget id="calculator">20 / 5</gadget>
<output>4</output>

<gadget id="calculator">4 + 1</gadget>
<output>5</output>

<gadget id="calculator">7 * 5</gadget>
<output>35</output>

<result>35</result>