In a class reunion, there were 8 classmates and 2 teachers. Every two people have to shake hands once, how many times did they shake hands in total?
在一次同学聚会中，一共到了8位同学和2位老师．每两人都要握一次手，一共握了几次手？
<gadget id="calculator">8 + 2</gadget>
<output>10</output>

<gadget id="calculator">10 - 1</gadget>
<output>9</output>

<gadget id="calculator">10 / 2</gadget>
<output>5</output>

<gadget id="calculator">9 * 5</gadget>
<output>45</output>

<result>45</result>