Giving 40 points and brainiest to answer these trigonometry questions

Ben is three times as old as samantha, who is two years older than half of michel's age. if michel is 12. how old is ben?

Two customers went to a post office. first customer paid $12 for 14 and 5 envelopes the second paid 24.80 for 10 postcards and 15 envelopes. what is cost of each envelope?

How do you determine whether a relationship represented as as graph is linear or nonlinear