A chemical factory completed 57% of the annual plan in the first half of the year; completed 64% of the annual plan in the second half of the year, and how much the annual plan was overfulfilled.
某化工厂上半年完成全年计划的57%；下半年完成全年计划的64%，全年超额完成计划的多少．
<gadget id="calculator">57 / 100</gadget>
<output>57/100 = around 0.57</output>

<gadget id="calculator">64 / 100</gadget>
<output>16/25 = around 0.64</output>

<gadget id="calculator">(16/25) - 1</gadget>
<output>-9/25 = around -0.36</output>

<gadget id="calculator">(57/100) + (-9/25)</gadget>
<output>21/100 = around 0.21</output>

<result>21/100 = around 0.21</result>