Master Wang plans to make a batch of parts. On the first day, he made the planned one (4/7), and on the second day he made the rest (3/5). At this time, there are still 42 parts left to be made. How much does Master Wang plan to make? parts?
王师傅计划做一批零件，第一天做了计划的(4/7)，第二天又做了余下的(3/5)，这时还剩42个零件没做，王师傅计划做多少个零件？
<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">1 - (3/5)</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">4 / 7</gadget>
<output>4/7 = around 0.571429</output>

<gadget id="calculator">1 - (4/7)</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">42 / (2/5) / (3/7)</gadget>
<output>245</output>

<result>245</result>