Ineed the answers and how you get them

Which is an equation for the nth terms of the sequence 12,15,18,21

Someone this asap for a group of students attends a basketball game. * the group buys x hot dogs at the concession stand for $2 each. * the group buys y drinks at the concession stand for $3 each. the group buys 29 items at the concession stand for a total of $70. how many hot dogs did the group buy?

Which graph represents the linear function below? y-3=1/2(x+2)