Some coal is transported, and 25% of the coal is transported on the first day, which is exactly 100 tons. How many tons of these coals are there?
运一些煤，第一天运了这些煤的25%，正好是100t，这些煤共有多少t．
<gadget id="calculator">25 / 100</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">100 / (1/4)</gadget>
<output>400</output>

<result>400</result>