A number is subtracted from the numerator and denominator of (23/30) at the same time, and the new fraction is (3/4) after division. What is the number subtracted at the same time?
(23/30)的分子和分母同时减去一个数，新的分数约分后是(3/4)，同时减去的数是多少．
<gadget id="calculator">30 - 28</gadget>
<output>2</output>

<result>2</result>