15% of a pile of coal is transported for the first time, 23% for the second time, and a total of 19 tons are transported for the two times. How many tons of this pile of coal are left?
一堆煤第一次运走全部的15%，第二次运走23%，两次共运走19吨．这堆煤还剩下多少吨？
<gadget id="calculator">15 / 100</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">23 / 100</gadget>
<output>23/100 = around 0.23</output>

<gadget id="calculator">(3/20) + (23/100)</gadget>
<output>19/50 = around 0.38</output>

<gadget id="calculator">19 / (19/50)</gadget>
<output>50</output>

<gadget id="calculator">1 - (19/50)</gadget>
<output>31/50 = around 0.62</output>

<gadget id="calculator">50 * (31/50)</gadget>
<output>31</output>

<result>31</result>