Consider the quadratic function $\ w(x) = -4 x^2 - 28 x + 23$.

(a) The vertex of this parabola is at the point? help (points)
(Enter a point as $(h,k)$ including parentheses. Give exact coordinates, not approximations.)

(b) What is the axis of symmetry for this parabola? help (equations)
(Enter your answer in the form of an equation for a vertical line of symmetry, not just a number.)