After transferring from class A (1/7) to class B, the number of people in the two classes is equal. The original number of people in class B is the same as that of class A.
从甲班调(1/7)到乙班后两班的人数就相等，原来乙班人数是甲班的多少．
<gadget id="calculator">7 - 1 - 1</gadget>
<output>5</output>

<gadget id="calculator">5 / 7</gadget>
<output>5/7 = around 0.714286</output>

<result>5/7 = around 0.714286</result>