(3/5) of a number is 12 more than (3/7) of this number. Find this number?
一个数的(3/5)比这个数的(3/7)多12，求这个数？
<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">3 / 7</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">(3/5) - (3/7)</gadget>
<output>6/35 = around 0.171429</output>

<gadget id="calculator">12 / (6/35)</gadget>
<output>70</output>

<result>70</result>