There are 150 tons of steel in the warehouse, 20% of the total is used for the first time, and (1/3) of the total is used for the second time. How many tons of steel are left?
仓库有150吨钢材，第一次用去总数的20%，第二次用去总数的(1/3)．还剩下多少吨钢材？
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

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

<gadget id="calculator">1 - (1/5) - (1/3)</gadget>
<output>7/15 = around 0.466667</output>

<gadget id="calculator">150 * (7/15)</gadget>
<output>70</output>

<result>70</result>