Master Li has processed a batch of parts, 390 of which have been processed, which is 60 less than planned (3/7). How many parts does Master Li plan to process?
李师傅加工一批零件，已经加工好了390个，比计划的(3/7)少60个．李师傅计划加工零件多少个？
<gadget id="calculator">390 + 60</gadget>
<output>450</output>

<gadget id="calculator">3 / 7</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">450 / (3/7)</gadget>
<output>1_050</output>

<result>1_050</result>