The two masters and apprentices process a batch of parts. The master alone takes 20 days to complete, while the apprentice makes 27 parts every day. They always cooperate. When they complete this batch of parts together, the number completed by the apprentice is the total (2/5) , How many parts are there in total?
师徒二人加工一批零件，师傅单独做要20天完成，而徒弟每天做27个零件，他们始终合作，当他们共同完成这批零件时，徒弟完成的数量是总数的(2/5)，求这批零件共多少个？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (2/5)</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">(3/5) / (2/5)</gadget>
<output>3/2 = around 1.5</output>

<gadget id="calculator">(3/2) * 20 * 27</gadget>
<output>810</output>

<result>810</result>