It takes 4 hours for Master Wang to process a batch of parts alone, but Master Li's work efficiency is 20% higher than that of Master Wang. How many hours can the two work together to complete this batch of parts?
加工一批零件，王师傅独做要4小时完成，李师傅的工作效率比王师傅的高20%，两人合做这一批零件只要几小时就能完成？
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 + (1/5)</gadget>
<output>6/5 = around 1.2</output>

<gadget id="calculator">(1/4) * (6/5)</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">(1/4) + (3/10)</gadget>
<output>11/20 = around 0.55</output>

<gadget id="calculator">1 / (11/20)</gadget>
<output>20/11 = around 1.818182</output>

<result>20/11 = around 1.818182</result>