4-1/2-(1/2)*7.
4-1/2-(1/2)*7．
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">(1/2) * 7</gadget>
<output>7/2 = around 3.5</output>

<gadget id="calculator">4 - (1/2) - (7/2)</gadget>
<output>0</output>

<result>0</result>