((1/2)+(2/5))*(4/9).
((1/2)+(2/5))*(4/9)．
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">(1/2) + (2/5)</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">4 / 9</gadget>
<output>4/9 = around 0.444444</output>

<gadget id="calculator">(9/10) * (4/9)</gadget>
<output>2/5 = around 0.4</output>

<result>2/5 = around 0.4</result>