SOLUTION: a disk jocky must play 12 commercial spots during an 1 hour of radio. each commercial is either 30 or 60 seconds long. If the total commercial time during 1 hour is 8 min how man

Question 268919: a disk jocky must play 12 commercial spots during an 1 hour of radio. each commercial is either 30 or 60 seconds long. If the total commercial time during 1 hour is 8 min how many 30 second and 60 second commercials were played.
30=
60=
Answer by CharlesG2(834) (Show Source): You can put this solution on YOUR website!
a disk jocky must play 12 commercial spots during an 1 hour of radio. each commercial is either 30 or 60 seconds long. If the total commercial time during 1 hour is 8 min how many 30 second and 60 second commercials were played.
30=
60=
x 30 second commercials
y 60 second commercials
x + y = 12
1/2 * x + y = 8 (30 seconds is 1/2 minute)
(subsitute in y=12-x)
1/2 * x + 12 - x = 8
-1/2 * x + 12 = 8
-1/2 * x = -4 (divide both sides by -1)
1/2 * x = 4
x = 8 so 8 30 second commercials (4 minutes total)
and 4 60 second commercials (4 minutes total)

RELATED QUESTIONS
I really cannot figure this out! Please help!!! A disk jockey must play 12 commercial... (answered by ankor@dixie-net.com)

Is there some way someone can help me with this? I get lost after the first sentence. A... (answered by RAY100)

A disc jockey must play 16 commercial spots during 1 hour of a radio show. Each... (answered by stanbon)

A disc jockey must play 14 commercial spots during 1 hour of each radio shows. Each... (answered by rwm)

a disc jockey must play 14 commercial spots during 1 hour of a radio show. Each... (answered by mangopeeler07)

A disc jockey must play 16 commercial spots during 1 hour of a radio show. Each... (answered by richwmiller,Stitch)

A disc jockey must play 14 commercial spots during 1 hour of a radio show. Each... (answered by stanbon)

A disc jockey must play 14 commercial spots during 1 hour of a radio show. Each... (answered by ewatrrr)