The grain depot in Dongcheng District shipped out more than half of all grains by 2 tons on the first day, and the remaining half by 0.8 tons on the second day. After 6 tons of grains were shipped out on the third day, there were still 4 tons left. How many tons of grain originally coexisted in the grain depot.
东城区粮库，第一天运出所有粮食的一半多2吨，第二天又运出余下的一半少0.8吨，第三天运出6吨粮食后，还有4吨．粮库中原来共存粮食多少吨．
<gadget id="calculator">4 - 0.8</gadget>
<output>3.2</output>

<gadget id="calculator">6 + 3.2</gadget>
<output>9.2</output>

<gadget id="calculator">9.2 * 2</gadget>
<output>18.4</output>

<gadget id="calculator">18.4 + 2</gadget>
<output>20.4</output>

<gadget id="calculator">20.4 * 2</gadget>
<output>40.8</output>

<result>40.8</result>