Simple operation: (3/7)*60-4*(3/7).
简便运算：(3/7)*60-4*(3/7)．
<gadget id="calculator">3 / 7</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">(3/7) * 60</gadget>
<output>180/7 = around 25.714286</output>

<gadget id="calculator">4 * (3/7)</gadget>
<output>12/7 = around 1.714286</output>

<gadget id="calculator">(180/7) - (12/7)</gadget>
<output>24</output>

<result>24</result>