A pile of coal is transported away (1/4) for the first time, and 140 tons are transported for the second time. At this time, the ratio of the tons of remaining coal to the tons transported is 2:3. How many tons is this pile of coal?
一堆煤，第一次运走它(1/4)，第二次又运走140吨，这时余下的煤的吨数与运走的吨数的比是2：3．这堆煤原有多少吨？
<gadget id="calculator">2 + 3</gadget>
<output>5</output>

<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(3/5) - (1/4)</gadget>
<output>7/20 = around 0.35</output>

<gadget id="calculator">140 / (7/20)</gadget>
<output>400</output>

<result>400</result>