Very similar to my Lesson 2, question 1. An independent variable is another way of saying a parameter. Parameters are independent because they can take on any real number value. The other variables are defined in terms of the parameters, so they
are dependent variables.
Be careful when listing your solution in part (d)! The given matrix is only in REF. Either row reduce it to RREF first or use back substitution in order to properly state the solution.