Calculation: (5/7)-(6/15).
计算：(5/7)-(6/15)．
<gadget id="calculator">5 / 7</gadget>
<output>5/7 = around 0.714286</output>

<gadget id="calculator">6 / 15</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">(5/7) - (2/5)</gadget>
<output>11/35 = around 0.314286</output>

<result>11/35 = around 0.314286</result>