It is known that a=(4/5)b, in the following three sentences, how much less a is than b is correct.
已知a=(4/5)b，下面的三句话中，a比b少多少是正确的．
<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">(4/5) / 1</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">1 - (4/5)</gadget>
<output>1/5 = around 0.2</output>

<result>1/5 = around 0.2</result>