A batch of parts is finished by the master alone in 8 hours, and by the apprentice in 10 hours alone. After 4 hours of simultaneous processing by the master and the apprentice, there are still 10 parts left unfinished. How many parts are there in this batch?
一批零件，师傅单独加工8小时完成，徒弟单独加工10小时完成，师傅徒弟二人同时加工4小时后还剩10个没有加工完，原来这批零件有多少个？
<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">(9/40) * 4</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">1 - (9/10)</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">10 / (1/10)</gadget>
<output>100</output>

<result>100</result>