There are 210 tons of yellow sand to be transported to the construction site. The first time (2/7) of the total is transported away, and the second time 40% of the total is transported away. How many tons must be transported to finish?
有210吨黄沙要运到建筑工地，第一次运走了总数的(2/7)，第二次运走总数的40%，还要运多少吨才能运完？
<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

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

<gadget id="calculator">210 * (11/35)</gadget>
<output>66</output>

<result>66</result>