20% of a barrel of oil is used for the first time, and (1/4) is used for the second time. How much is used for the two times?
一桶油第一次用去了20%，第二次用去(1/4)，两次共用去了多少．
<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">(1/5) + (1/4)</gadget>
<output>9/20 = around 0.45</output>

<result>9/20 = around 0.45</result>