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

<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

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

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