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put this solution on YOUR website!a disc jockey must play 14 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 11 minutes how many 30 second commercials were played that hour? How many 60 second commercials?
the total commercial time during 1 hour is 11 minutes
Convert 11 minutes to seconds
660 seconds
x=amount of 30 second commercials
y=amount of 60 second commercials
30x+60y=660
a disc jockey must play 14 commercials
x+y=14
So you have
Use the second equation and solve for x.
becomes
Plug that in for x in the first equation.
Distribute
Combine like terms
Subtract 420 from both sides
Divide by 30
plug that in for y in the second original equation
Check:
It's true!
So the dj played 6 thirty-second commercials and 8 sixty-second commercials
