A pile of coal weighs 39.8 tons. On the first day, 12.8 tons were transported away, which is 3.6 tons less than on the second day. How many tons are left after two days?
一堆煤重39.8吨，第一天运走12.8吨，比第二天少运3.6吨，两天后还剩多少吨？
<gadget id="calculator">12.8 - 3.6</gadget>
<output>9.2</output>

<gadget id="calculator">39.8 - 12.8 - 9.2</gadget>
<output>17.8</output>

<result>17.8</result>