There is a batch of coal in a coal factory. On the first day (2/5) of the total amount is transported away, and on the second day (1/3) of the total amount is transported away, there are still 80 tons left. How many tons of original coal are there?
某煤厂有一批煤，第一天运走总数的(2/5)，第二天运走总数的(1/3)，还剩下80吨，原有煤多少吨？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">1 - (2/5) - (1/3)</gadget>
<output>4/15 = around 0.266667</output>

<gadget id="calculator">80 / (4/15)</gadget>
<output>300</output>

<result>300</result>