Answer and work someone please???

Last saturday, the museum box office sold 281 tickets for a total of $3,954. adults ticket cost $15, and students ticket cost $12. how many of each kind of tickets were sold?

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

If square root x = -7, then x= -49 true or false