pile of coal is shipped out in three days, the first day (2/5) and 55 tons on the second day. The ratio of the third day to the sum of the first and second day is 2:5. How many tons will it take?
一堆煤用三天运完，第一天运走(2/5)，第二天运走55吨，第三天运的与第一、第二天和的比是2：5，第一天运走多少吨．
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">5 + 2</gadget>
<output>7</output>

<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">1 - (2/5) - (2/7)</gadget>
<output>11/35 = around 0.314286</output>

<gadget id="calculator">55 / (11/35)</gadget>
<output>175</output>

<gadget id="calculator">175 * (2/5)</gadget>
<output>70</output>

<result>70</result>