Chapter 19, Problem 6QAP

What is the coordination number of the central metal atom in the following complexes?
(a) $\left[\text{Fe}{\left({\text{H}}_2\text{O}\right)}_6{}^{3+}\right]$
(b) $\left[\text{Pt}\left({\text{NH}}_3\right){\text{Br}}_3{}^{-}\right]$
(c) $\left[\text{V}\left(en\right){\text{Cl}}_4{}^{2-}\right]$
(d) $\left[\text{Au}{\left(\text{CN}\right)}_{\text{2}}{}^{+}\right]$