Did you read my tips on how to study and learn this course?  If not, here is a link to those important suggestions:

Here is a link to the actual assignment, in case you don't have it handy:

Study Lesson 1 (Systems of Linear Equations), Lesson 2 (Row-Reduction and Linear Systems) and Lesson 3 (Matrix Math) from my Linear Algebra & Vector Geometry book to prepare for this assignment. 

Do note that my free sample above does include both Lessons 1 and 2 in my book and audio lectures.

I define a RREF and REF matrix in the first couple of pages of Lesson 2.

Very similar to my Lesson 2, question 4.  You should use REF and back substitution.

In part (b), you will have parameters for sure (look at my section discussing homogeneous systems in Lesson 2 to understand how I know this without any work). Once your matrix is in REF, identify your parameters, and be sure to sub those in while performing your back substitution to solve the rest of the variables.

Very similar to my Lesson 2, question 3.

Very similar to my Lesson 2, questions 6, 7 and 8.

This is just classic matrix math stuff as taught in Lesson 3 of my book.  Very similar to my Lesson 3, question 1.

Similar to the style of my Lesson 2, questions 5 and 6.