The distance between the teaching building and the library is 60 meters. The greening team should plant trees on both sides of the road between them (not at both ends). The distance between two adjacent trees is 3 meters. How many trees can be planted.
教学楼与图书馆之间相距60米，绿化队要在它们之间路两旁栽树(两端不栽)，相邻两棵树之间的距离是3米，可种树多少棵．
<gadget id="calculator">60 / 3</gadget>
<output>20</output>

<gadget id="calculator">20 - 1</gadget>
<output>19</output>

<gadget id="calculator">19 * 2</gadget>
<output>38</output>

<result>38</result>