A football match is held in the city. Each of the 15 districts sends a representative team. Each team has to play one game with other teams. These games are held in the district stadiums of the 15 districts. How many games are held in each stadium on average? Contest?
市里举行足球比赛，有15个区各派出1个代表队，每个队都要与其他各队比赛一场，这些比赛分别在15个区的区体育场进行，平均每个体育场要举行多少场比赛？
<gadget id="calculator">15 - 1</gadget>
<output>14</output>

<gadget id="calculator">15 / 2 / 15</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">14 * (1/2)</gadget>
<output>7</output>

<result>7</result>