A and B process the same batch of parts, and the work efficiency ratio of A and B is 2:3. It is known that A alone needs 9 hours to complete, and now two people work together. How many small ones are needed to complete?
甲、乙两人加工同一批零件，甲、乙两人的工作效率比是2：3．已知甲单独完成需9小时，现两人共同加工．需要多少小的完成？
<gadget id="calculator">1 / 9</gadget>
<output>1/9 = around 0.111111</output>

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

<gadget id="calculator">(1/9) * (3/2)</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">(1/9) + (1/6)</gadget>
<output>5/18 = around 0.277778</output>

<gadget id="calculator">1 / (5/18)</gadget>
<output>18/5 = around 3.6</output>

<result>18/5 = around 3.6</result>