A TV factory plans to produce 4,000 TV sets in May, but actually produced the planned (3/5) in the second half of the month, and produced the planned (7/10) in the second half of the month. How many TV sets are actually overproduced this month?
某电视机厂计划五月份生产4000台电视机，实际上半月生产了计划的(3/5)，下半月生产了计划的(7/10)．这个月实际超额生产电视机多少台？
<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">7 / 10</gadget>
<output>7/10 = around 0.7</output>

<gadget id="calculator">(7/10) - 1</gadget>
<output>-3/10 = around -0.3</output>

<gadget id="calculator">(3/5) + (-3/10)</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">4_000 * (3/10)</gadget>
<output>1_200</output>

<result>1_200</result>