(3/5)*((1/7)+(8/21)/(2/3)).
(3/5)*((1/7)+(8/21)/(2/3))．
<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">1 / 7</gadget>
<output>1/7 = around 0.142857</output>

<gadget id="calculator">8 / 21</gadget>
<output>8/21 = around 0.380952</output>

<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">(8/21) / (2/3)</gadget>
<output>4/7 = around 0.571429</output>

<gadget id="calculator">(1/7) + (4/7)</gadget>
<output>5/7 = around 0.714286</output>

<gadget id="calculator">(3/5) * (5/7)</gadget>
<output>3/7 = around 0.428571</output>

<result>3/7 = around 0.428571</result>