A pile of coal, one-third of it is transported away in the first time, and another 140 tons are transported away in 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，第一次运走它的三分之一，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">3 + 2</gadget>
<output>5</output>

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

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

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

<gadget id="calculator">140 / (4/15)</gadget>
<output>525</output>

<result>525</result>