A wire is (3/5) kilometers long, (1/4) is used for the first time, and (3/20) is used for the second time, what fraction of the wire is left?
一根电线长(3/5)千米，第一次用去(1/4)，第二次用去(3/20)，还剩这根电线的几分之几？
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">3 / 20</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">1 - (1/4) - (3/20)</gadget>
<output>3/5 = around 0.6</output>

<result>3/5 = around 0.6</result>