You multiply 15,000 by .1, which equals 1,500. Then you add that to 15,000. This equals 16,500. That is your answer.
The advertisers treat teenagers as separate target audiences by having to advertise products that would attract the teenagers alone as the teenagers are not particularly attracted to things that they may target the adult audiences, that is why, they laid out products that would target the teenagers in means of separating the target audiences.
The Central Nervous system is made out of spinal cords that connect to the brain.
