Calculation: 1+2-3*4/5.
计算：1+2-3*4/5．
<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">3 * (4/5)</gadget>
<output>12/5 = around 2.4</output>

<gadget id="calculator">2 - (12/5)</gadget>
<output>-2/5 = around -0.4</output>

<gadget id="calculator">1 + (-2/5)</gadget>
<output>3/5 = around 0.6</output>

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