What is the quotient of the difference between 1/5 and 1/7 divided by the difference between 7/10 and 1/2?
1/5与1/7的差除7/10与1/2的差，商是多少？
<gadget id="calculator">7 / 10</gadget>
<output>7/10 = around 0.7</output>

<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">(7/10) - (1/2)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 / 7</gadget>
<output>1/7 = around 0.142857</output>

<gadget id="calculator">(1/5) - (1/7)</gadget>
<output>2/35 = around 0.057143</output>

<gadget id="calculator">(1/5) / (2/35)</gadget>
<output>7/2 = around 3.5</output>

<result>7/2 = around 3.5</result>