Consider the following system of equations.    w + x + y + z = 6 w + y + z = 4 w + y = 2 (∗) (a) List the leading variables . (b) List the free variables . (c) The general solution of (∗) (expressed in terms of the free variables) is ( , , , ) . (d) Suppose that a fourth equation −2w + y = 5 is included in the system (∗). What is the solution of the resulting system? Answer: ( , , , ). (e) Suppose that instead of the equation in part (d), the equation −2w − 2y = −3 is included in the system (∗). Then what can you say about the solution(s) of the resulting system? Answer: .