Teacher Wang's house needs 2 carpenters and 2 electricians to decorate a new house. There are 3 carpenters, 3 electricians, and 1 person who can be both a carpenter and an electrician. How many different ways are there to choose 4 of these 7 people to do the job?
王老师家装修新房，需要2个木匠和2个电工．现有木匠3人、电工3人，另有1人既能做木匠也能做电工．要从这7人中挑选出4人完成这项工作，共有多少种不同的选法？
<gadget id="calculator">3 ** 2</gadget>
<output>9</output>

<gadget id="calculator">18 - 9</gadget>
<output>9</output>

<gadget id="calculator">18 + 9</gadget>
<output>27</output>

<result>27</result>