A 3-meter piece of steel, (1/4) is used up, and (1/4) meter is used up, how many meters are left.
一根3米的钢材，用去了(1/4)，又用去了(1/4)米，还剩多少米．
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

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

<gadget id="calculator">3 - (3/4) - (1/4)</gadget>
<output>2</output>

<result>2</result>