Aunt Wang collected (1/2) tons of melons, sold (1/5) tons on the first day, and sold (1/6) tons the next day. How many tons are left unsold?
王大妈收了(1/2)吨瓜，第一天卖出(1/5)吨，第二天卖出(1/6)吨，还剩多少吨没卖出？
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

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

<gadget id="calculator">1 / 6</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">(1/2) - (1/5) - (1/6)</gadget>
<output>2/15 = around 0.133333</output>

<result>2/15 = around 0.133333</result>