It is known that AB=(2/5), B/A=(3/5), then A=how much.
已知A-B=(2/5)，B/A=(3/5)，则A=多少．
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

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

<result>1</result>