(3/5) of the number of A is (1/3) of the sum of the two numbers of A and B, and the number of A accounts for the sum of the two numbers of A and B ((())/(())).
甲数的(3/5)是甲、乙两数和的(1/3)，甲数占甲、乙两数和的((())/(()))．
<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

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

<gadget id="calculator">(1/3) / (3/5)</gadget>
<output>5/9 = around 0.555556</output>

<result>5/9 = around 0.555556</result>