The refrigerator factory plans to produce 2,000 refrigerators in May. In fact, the plan was completed in half a month (3/5), and the plan was completed in the second half month (13/20). How many units were actually produced more than planned in May?
电冰箱厂五月份计划生产电冰箱2000台．实际上半月完成计划的(3/5)，下半月完成计划的(13/20)五月份实际比计划超产多少台？
<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">13 / 20</gadget>
<output>13/20 = around 0.65</output>

<gadget id="calculator">(13/20) - 1</gadget>
<output>-7/20 = around -0.35</output>

<gadget id="calculator">(3/5) + (-7/20)</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">2_000 * (1/4)</gadget>
<output>500</output>

<result>500</result>