El 10 es numero racional?

Ineed to know the answer to this algebra question.

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.

Solve the following pair of equations for x and y: ax/b_ by /a= a +b; ax - by = 2ab