The original 100 tons of steel in the warehouse used 20% of the total for the first time, and 1/4 of the total for the second time. How many tons are left now?
仓库原有100t钢材，第一次用去总数的20%，第二次用去总数的(1/4)，现在还剩多少t？
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 - (1/5) - (1/4)</gadget>
<output>11/20 = around 0.55</output>

<gadget id="calculator">100 * (11/20)</gadget>
<output>55</output>

<result>55</result>