There are 30 fish in tank A, which is 12 more than tank B, and the number of fish taken from tank A is put into tank B. At this time, the number of tails of fish in the two tanks is just equal.
甲缸有鱼30尾，比乙缸多12尾，从甲缸取出多少放入乙缸，这时两缸鱼的尾数正好相等．
<gadget id="calculator">12 / 2 / 30</gadget>
<output>1/5 = around 0.2</output>

<result>1/5 = around 0.2</result>