For a pile of sand, 40% is transported away for the first time. 30% was transported away for the second time, leaving 48 tons. How many tons is this pile of sand?
一堆沙子，第一次运走40%．第二次运走30%，还剩下48吨．这堆沙子有多少吨？
<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

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

<gadget id="calculator">(2/5) + (3/10)</gadget>
<output>7/10 = around 0.7</output>

<gadget id="calculator">1 - (7/10)</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">48 / (3/10)</gadget>
<output>160</output>

<result>160</result>