The master and apprentice work together to process 520 parts. The master processes 30 parts per hour, and the apprentice processes 20 per hour. How long will it take for the master and apprentice to finish processing?
师徒两人合作加工520个零件，师傅每小时加工30个，徒弟每小时加工20个，师徒二人多长时间能加工完？
<gadget id="calculator">30 + 20</gadget>
<output>50</output>

<gadget id="calculator">520 / 50</gadget>
<output>52/5 = around 10.4</output>

<result>52/5 = around 10.4</result>