The Guangming Workshop produces a batch of parts, 35% of which have been produced, and after 420 more parts are produced, the ratio of the number of unproduced parts to the number of produced parts is 2:3. How many parts are there in this batch?
光明车间生产一批零件，已经生产了这批零件的35%，再生产420个后，未生产的与已生产的个数比是2：3，这批零件一共有多少个？
<gadget id="calculator">2 + 3</gadget>
<output>5</output>

<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">35 / 100</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">420 / (1/4)</gadget>
<output>1_680</output>

<result>1_680</result>