How many 3-digit nubmers can be made using each of these digits only once 3,6,9

How do you solving the solution of each system using elimination?

Campus rentals rents 2 and 3 bedrooms apartments for $700 ans $900 a month respectively. last month they had six vacant apartments and reported $4600 in lost rent. how many of each type of apartment were vacant?

Madeline takes her family on a boat ride. going through york canal, she drives 6 miles in 10 minutes. later on as she crosses stover lake, she drives 30 minutes at the same average speed. which statement about the distances is true?