How many consecutive 4s are subtracted from 120, and the remainder is exactly 40.
从120里连续减去多少个4，剩下的正好是40．
<gadget id="calculator">120 - 40</gadget>
<output>80</output>

<gadget id="calculator">80 / 4</gadget>
<output>20</output>

<result>20</result>