The engineering team opened a 120-meter-long cave, which was planned to be completed in 24 days, but it was actually completed 4 days earlier than the original plan. The actual average per day was how many meters the cave was opened.
工程队开一个120米长的山洞，计划24天完成，实际比原计划提前4天完成，实际平均每天开山洞多少米．
<gadget id="calculator">24 - 4</gadget>
<output>20</output>

<gadget id="calculator">120 / 20</gadget>
<output>6</output>

<result>6</result>