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 time is 1 hour 8 min, how many 30 and sixty seconds commercials were played?

Question

anonymous · Answer

We will denote 30 second  commercial as 'a'
                      60 second  commercial as 'b'

anonymous · Answer

There are 12 commercial spot
a+b=12

anonymous · Answer

?

anonymous · Answer

can you check all your numbers again?

anonymous · Answer

if the total commercial time during the 1 hour is 8 minutes

anonymous · Answer

i wrote it wrong

anonymous · Answer

$$a+b\text{=}12$$
$$\frac{1}{120}a+\frac{1}{60}b=\frac{8}{60}$$

Solve for a , b
a=8
b=4