(2/5) of X is (4/5), find X.
X的(2/5)是(4/5)，求X．
<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

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

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

<result>2</result>