After 10 tons of coal are burned (2/5), then (2/5) tons are burned, how many tons are left now?
10吨煤烧了(2/5)后，又烧了(2/5)吨，现在剩多少吨．
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">10 * (2/5)</gadget>
<output>4</output>

<gadget id="calculator">10 - 4 - (2/5)</gadget>
<output>28/5 = around 5.6</output>

<result>28/5 = around 5.6</result>