Adding (2/5) to a number and subtracting (5/6) results in (11/15). Find this number?
一个数加上(2/5)再减去(5/6)结果是(11/15)，求这个数？
<gadget id="calculator">11 / 15</gadget>
<output>11/15 = around 0.733333</output>

<gadget id="calculator">5 / 6</gadget>
<output>5/6 = around 0.833333</output>

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

<gadget id="calculator">(5/6) - (2/5)</gadget>
<output>13/30 = around 0.433333</output>

<gadget id="calculator">(11/15) + (13/30)</gadget>
<output>7/6 = around 1.166667</output>

<result>7/6 = around 1.166667</result>