(2/3)-(1/2)x+(1/5)=(2/3).
(2/3)-(1/2)x+(1/5)=(2/3)．
<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">(1/5) - (2/3)</gadget>
<output>-7/15 = around -0.466667</output>

<gadget id="calculator">(2/3) + (-7/15)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">(1/5) / (1/2)</gadget>
<output>2/5 = around 0.4</output>

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