A disc jockey must play 12 commercial spots during 1 hour of a radio show. Each commercial is either 30 sec or 60 sec long. If the total commercial time during 1 hour is 8 min, how many 30-sec commercials were played for that hour? How many 60- sec commercials?

Question

A disc jockey must play 12 commercial spots during 1 hour of a radio show. Each commercial is either 30 sec or 60 sec long. If the total commercial time during 1 hour is 8 min, how many 30-sec commercials were played for that hour?  How many 60- sec commercials?

anonymous · Answer

x + y =12
.5x + y = 8 
.5x = 4  x = 8 & y =4