For a), just do any of the row operations and that matrix will be row equivalent to A.
For b), Just set the equation up,
Where T refers to the transpose. solve for a, b, and c. You could even use a few guesses to see what you get, if you wanted.
For c), You need to show that the first three column vectors satisfy this property:
A set of vectors, are linearly independent if and only if implies that .