If 4a=(2/5)b, then a:b=how much.
如果4a=(2/5)b，则a：b=多少．
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">(2/5) / 4</gadget>
<output>1/10 = around 0.1</output>

<result>1/10 = around 0.1</result>