Aunt Wang collected (1/2) tons of melons, sold (1/5) of the total on the first day, and sold (1/6) of the total on the second day, what fraction of the total is left unsold?
王大妈收了(1/2)吨瓜，第一天卖出总数的(1/5)，第二天卖出总数的(1/6)，还剩总数的几分之几没卖出？
<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 - (1/5) - (1/6)</gadget>
<output>19/30 = around 0.633333</output>

<result>19/30 = around 0.633333</result>