Processing a batch of parts A alone takes 6 hours to complete, and B alone takes 10 hours to complete. After A and B worked together for 3 hours, there were 120 unprocessed parts. How many parts are there in total?
加工一批零件甲单独做6小时完成，乙单独作要10小时完成．甲乙共同做了3小时后还剩120个没有加工，这批零件共有多少个？
<gadget id="calculator">1 / 6</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">(1/6) + (1/10)</gadget>
<output>4/15 = around 0.266667</output>

<gadget id="calculator">(4/15) * 3</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">1 - (4/5)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">120 / (1/5)</gadget>
<output>600</output>

<result>600</result>