A piece of cloth is used to make a coat (2/5) and trousers (1/3), how much is left?
一段布，做上衣用去(2/5)，做裤子用去(1/3)，还剩下几分之几？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">1 - (2/5) - (1/3)</gadget>
<output>4/15 = around 0.266667</output>

<result>4/15 = around 0.266667</result>