Choose 5 people from 10 people to go to the meeting, among them Xiuxiu, Qingqing and Meimei must go, so how many different ways are there to choose?
从10人中选5人去开会，其中秀秀、青青、梅梅三人必须去，那么有多少种不同的选法．
<gadget id="calculator">10 - 3</gadget>
<output>7</output>

<gadget id="calculator">6 / 2</gadget>
<output>3</output>

<gadget id="calculator">7 * 3</gadget>
<output>21</output>

<result>21</result>