Processing a batch of parts, A alone takes 8 hours to complete, B alone takes 10 hours to complete, and A and B work together to process 207 parts in 4 hours. How many parts are there in this batch?
加工一批零件，甲单独要8小时完成，乙单独要10小时完成，甲乙合作4小时正好加工207个，这批零件有多少个？
<gadget id="calculator">1 / 8</gadget>
<output>1/8 = around 0.125</output>

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

<gadget id="calculator">(1/8) + (1/10)</gadget>
<output>9/40 = around 0.225</output>

<gadget id="calculator">207 / 4 / (9/40)</gadget>
<output>230</output>

<result>230</result>