Solution sets and their dimensions

Ok i have an augmented matrix which is big so i won't type it out, but i've reduced it all fine.

But i require to write it in the form

{a_1 v_1 + a_2 v_2 + ...+ a_n v_n + z | a_1 ...a_n ∈R } v is vector, z is vector a's ar constants

Now i think i have got this bit, i jut split teh coloums up and the constant is the smallest division before the vectors hit fractions ??

If true, im stuck on the next bit which is "the dimension of the solution set" what defines this and how would i check the answer?

Thanks

Re: Solution sets and their dimensions

I've been looking for a youtube video or some notes to help explain it but i can't find (or can't spot) what i require.