There are (3/4) tons of coal in the cafeteria, and (2/5) is left after part of it is used up. How many tons are left.
食堂有(3/4)吨煤，用去一部分后还剩(2/5)．还剩多少吨．
<gadget id="calculator">3 / 4</gadget>
<output>3/4 = around 0.75</output>

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

<gadget id="calculator">(3/4) * (2/5)</gadget>
<output>3/10 = around 0.3</output>

<result>3/10 = around 0.3</result>