(2/5) of A number is (2/7) of B number, and (3/5) of A number is the number of B number.
甲数的(2/5)是乙数的(2/7)，甲数的(3/5)是乙数的多少．
<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">(2/7) / (2/5)</gadget>
<output>5/7 = around 0.714286</output>

<gadget id="calculator">7 * (5/7)</gadget>
<output>5</output>

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

<gadget id="calculator">(3/5) / 7</gadget>
<output>3/35 = around 0.085714</output>

<gadget id="calculator">5 * (3/35)</gadget>
<output>3/7 = around 0.428571</output>

<result>3/7 = around 0.428571</result>