What is the quotient of the difference between 4 and (1/2) divided by their sum? (column comprehensive formula)
4与(1/2)的差除以它们的和，商是多少？(列综合算式)
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">4 - (1/2)</gadget>
<output>7/2 = around 3.5</output>

<gadget id="calculator">4 + (1/2)</gadget>
<output>9/2 = around 4.5</output>

<gadget id="calculator">(7/2) / (9/2)</gadget>
<output>7/9 = around 0.777778</output>

<result>7/9 = around 0.777778</result>