The sum of (3/5) and (2/7) of a number is (12/35), what is this number?
一个数的(3/5)与(2/7)的和是(12/35)，这个数是多少．
<gadget id="calculator">12 / 35</gadget>
<output>12/35 = around 0.342857</output>

<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">(12/35) - (2/7)</gadget>
<output>2/35 = around 0.057143</output>

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

<gadget id="calculator">(2/35) / (3/5)</gadget>
<output>2/21 = around 0.095238</output>

<result>2/21 = around 0.095238</result>