On a certain railway line, there were originally 7 stations including the starting point and the ending point, but now 3 new stations have been added. The round-trip tickets between the two stations on the railway are different. So, how many different kinds of tickets need to be added?
某条铁路线上，包括起点和终点在内原来共有7个车站，现在新增了3个车站，铁路上两站之间往返的车票不一样，那么，这样需要增加多少种不同的车票？
<gadget id="calculator">7 + 3</gadget>
<output>10</output>

<gadget id="calculator">10 * 9</gadget>
<output>90</output>

<gadget id="calculator">7 * 6</gadget>
<output>42</output>

<gadget id="calculator">90 - 42</gadget>
<output>48</output>

<result>48</result>