long (9/10) meter wire, cut off (1/10) of it for the first time, and (2/5) of it for the second time, what fraction of the total length is left?
一根长(9/10)米的铁丝，第一次剪去它的(1/10)，第二次剪去它的(2/5)，还剩全长的几分之几？
<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

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

<gadget id="calculator">1 - (1/10) - (2/5)</gadget>
<output>1/2 = around 0.5</output>

<result>1/2 = around 0.5</result>