There is a batch of parts in the machinery factory. The master alone takes 5 hours less to process than the apprentice. The master processes 12 per hour, and the apprentice processes 10 per hour. How many parts are there in this batch?
机械厂有一批零件，师傅单独加工比徒弟少用5小时，师傅每小时加工12个，徒弟每小时加工10个，这批零件有多少个？
<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">1 / 12</gadget>
<output>1/12 = around 0.083333</output>

<gadget id="calculator">(1/10) - (1/12)</gadget>
<output>1/60 = around 0.016667</output>

<gadget id="calculator">5 / (1/60)</gadget>
<output>300</output>

<result>300</result>