A pile of yellow sand weighs 400 tons. (1/4) is transported away on the first day, and 30% is transported away on the second day. How many tons are left?
一堆黄沙重400吨，第一天运走了(1/4)，第二天运走30%，还剩多少吨？
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">30 / 100</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">1 - (1/4) - (3/10)</gadget>
<output>9/20 = around 0.45</output>

<gadget id="calculator">400 * (9/20)</gadget>
<output>180</output>

<result>180</result>