There are 120 tons of steel in the warehouse, 20% of the total was used for the first time, and (1/2) of the total was used for the second time. How many tons of steel are left?
仓库里有120吨钢材，第一次用去了总数的20%，第二次用去了总数的(1/2)．还剩多少吨钢材？
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 - (1/5) - (1/2)</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">120 * (3/10)</gadget>
<output>36</output>

<result>36</result>