Plant trees on the side of a 320-meter path, and plant one tree every 16 meters from the starting point to the end point. How many classes can be planted?
在一条320米的小路一侧栽树，从起点到终点每隔16米栽1棵，可以栽多少课？
<gadget id="calculator">320 / 16</gadget>
<output>20</output>

<gadget id="calculator">20 + 1</gadget>
<output>21</output>

<result>21</result>