How do I do this (With instructions if you could) (Will give brainliest)

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

Write an inequality and solve each problem.for exercises 11 and 12, interpret the solution.

Kayla made observations about the sellin price of a new brand of coffee that sold in the three different sized bags she recorded those observations in the following table 6 is $2.10 8 is $2.80 and 16 is to $5.60 use the relationship to predict the cost of a 20oz bag of coffee.