Processing a batch of parts, the master alone can complete it in 8 hours, and the apprentice alone can complete it in 10 hours. After the master and apprentice work together for 2.5 hours, what percentage of the batch of parts are the parts that have not yet been processed?
加工一批零件，师傅独做8小时完成，徒弟独做10小时完成，师徒二人合作2.5小时后，还没有加工的零件占这批零件的几分之几？
<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) * 2.5</gadget>
<output>0.5625</output>

<gadget id="calculator">1 - 0.5625</gadget>
<output>0.4375</output>

<result>0.4375</result>