The ratio of the dividend to the divisor is 20:21. The ratio of the dividend to the quotient is 3:5. What is the dividend.
被除数与除数的比是20：21．被除数与商的比是3：5．被除数是多少．
<gadget id="calculator">20 / 21</gadget>
<output>20/21 = around 0.952381</output>

<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">(20/21) * (3/5)</gadget>
<output>4/7 = around 0.571429</output>

<result>4/7 = around 0.571429</result>