Problema Solution
a disc jockey must play 12 commercial spots during 1 hour of a radio show. Each commercial is either 30 seconds or 60 seconds long. If the total commercial time during 1 hour is 8 min, how many 30 second commercials were played that hour? How many 60 second commercials?
Answer provided by our tutors
30a+60b=480
a+b=12
a=12-b
30(12-b)+60b=480
360+30b=480
30b=120
b=4
so 4 60 second commercials were played and 8 30 second commercials were played