Simple calculation: (7/9)*(5/8)-(7/9)/(8/5).
简便计算：(7/9)*(5/8)-(7/9)/(8/5)．
<gadget id="calculator">7 / 9</gadget>
<output>7/9 = around 0.777778</output>

<gadget id="calculator">5 / 8</gadget>
<output>5/8 = around 0.625</output>

<gadget id="calculator">(7/9) * (5/8)</gadget>
<output>35/72 = around 0.486111</output>

<gadget id="calculator">8 / 5</gadget>
<output>8/5 = around 1.6</output>

<gadget id="calculator">(7/9) / (8/5)</gadget>
<output>35/72 = around 0.486111</output>

<gadget id="calculator">(35/72) - (35/72)</gadget>
<output>0</output>

<result>0</result>