20/(63*((5/7)-(5/9))*(2/5)).
20/(63*((5/7)-(5/9))*(2/5))．
<gadget id="calculator">5 / 7</gadget>
<output>5/7 = around 0.714286</output>

<gadget id="calculator">5 / 9</gadget>
<output>5/9 = around 0.555556</output>

<gadget id="calculator">(5/7) - (5/9)</gadget>
<output>10/63 = around 0.15873</output>

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

<gadget id="calculator">63 * (10/63) * (2/5)</gadget>
<output>4</output>

<gadget id="calculator">20 / 4</gadget>
<output>5</output>

<result>5</result>