2. an advertising firm has an old computer that can prepare a whole mailing in 6 hours. with
the of a newer model the job is complete in 2 hours. how long would it take the newer
model to complete the job alone?

The new model can do the entire work alone in 3 hours.

Step-by-step explanation:

Let us assume that the newer model of computer can complete the job alone in x hours.

Therefore, in one hour this new model can do part of the job.

Again the old model can do the entire job alone in 6 hours,

So, in 1 hour the old model can do part of the job.

Therefore, if they work together, then in 1 hour they will do part of the job.

So, the entire work they can do together in hours.

So, given that  

⇒ 6x = 2x + 12

⇒ x = 3 hours,

Therefore, the new model can do the entire work alone in 3 hours. (Answer)

14.3

step-by-step explanation:

add all the numbers together.

9 + 12 + 15 + 16 + 17 + 17 = 86

now, divide 86 by how many numbers we have: 6.

86 / 6 = 14.3