There is a batch of steel on the construction site weighing (4/7) tons, and (1/4) is used up, how many tons are left?
工地上有一批钢材重(4/7)吨，用去了(1/4)，还剩多少吨？
<gadget id="calculator">4 / 7</gadget>
<output>4/7 = around 0.571429</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 - (1/4)</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">(4/7) * (3/4)</gadget>
<output>3/7 = around 0.428571</output>

<result>3/7 = around 0.428571</result>