(2/3)x+(1/5)x=(4/5).
(2/3)x+(1/5)x=(4/5)．
<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

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

<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(2/3) + (1/5)</gadget>
<output>13/15 = around 0.866667</output>

<gadget id="calculator">(4/5) / (13/15)</gadget>
<output>12/13 = around 0.923077</output>

<result>12/13 = around 0.923077</result>