The master and the apprentice have to process 300 parts in total. After working for 4 hours, the number of unprocessed parts is exactly the same. The ratio of the master's processed parts to his planned number is 5:8, and the ratio of the apprentice's processed parts to his planned number is 4:7. What is the number of parts that the master has not finished processing?
师徒两人一共要加工300个零件，工作4小时后两人未加工完的零件数正好相等．师傅已加工的零件与他的计划数比是5：8，徒弟已加工的零件数与他的计划数的比是4：7．师傅未加工完的零件数是多少个？
<gadget id="calculator">8 + 7</gadget>
<output>15</output>

<gadget id="calculator">8 / 15</gadget>
<output>8/15 = around 0.533333</output>

<gadget id="calculator">300 * (8/15)</gadget>
<output>160</output>

<gadget id="calculator">5 / 8</gadget>
<output>5/8 = around 0.625</output>

<gadget id="calculator">1 - (5/8)</gadget>
<output>3/8 = around 0.375</output>

<gadget id="calculator">160 * (3/8)</gadget>
<output>60</output>

<result>60</result>