A colored ribbon is 2m long, (1/4) of it is used for the first time, and (1/4)m is used for the second time, how much m is left?
一根彩带长2m，第一次用去它的(1/4)，第二次用去(1/4)m，还剩多少m．
<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">2 * (3/4)</gadget>
<output>3/2 = around 1.5</output>

<gadget id="calculator">(3/2) - (1/4)</gadget>
<output>5/4 = around 1.25</output>

<result>5/4 = around 1.25</result>