Make up a word problem solved by the formula (4/5)*20.
编一道用算式(4/5)*20解答的应用题．
<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">(4/5) * 20</gadget>
<output>16</output>

<result>16</result>