A pile of coal uses (4/5) tons on the first day, and (1/5) tons less than the first day on the second day, how many tons are used on the second day?
一堆煤，第一天用去(4/5)吨，第二天用去的比第一天少(1/5)吨，第二天用去多少吨？
<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(4/5) - (1/5)</gadget>
<output>3/5 = around 0.6</output>

<result>3/5 = around 0.6</result>