A disc jockey must play 14commercial spots during 1hour of radio show. Each commercial is either 30 seconds or 60 seconds long. If the total commercial time during 1hour is 11 minutes, how many 30 second commercials were played that hour? How many 60 second commercials?

x+y = 14

30x+60y = 660

6 @ 30"
8 @ 60"