A factory plans to produce a batch of parts. It takes 6 hours for A alone, 8 hours for B alone, and 4 hours for A and B at the same time. The result is 490 more parts than planned. How many parts are planned to be produced?
某工厂计划生产一批零件，甲单独做需要6时，乙单独做需要8时，甲、乙两人同时做4时，结果比计划多生产490个零件，计划生产零件多少个？
<gadget id="calculator">1 / 6</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">1 / 8</gadget>
<output>1/8 = around 0.125</output>

<gadget id="calculator">(1/6) + (1/8)</gadget>
<output>7/24 = around 0.291667</output>

<gadget id="calculator">(7/24) * 4</gadget>
<output>7/6 = around 1.166667</output>

<gadget id="calculator">(7/6) - 1</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">490 / (1/6)</gadget>
<output>2_940</output>

<result>2_940</result>