Chapter 21, Problem 7PE

What is the coordination number of the metal ion in $\left(\text{a}\right){\text{ [CoCl2(C}}_{\text{2}}{\text{O}}_{\text{4}}{\text{)}}_{\text{2}}{\text{]}}^{\text{3-}}\text{, }\left(\text{b}\right){\left[\text{Cr}{\left({\text{C}}_{\text{2}}{\text{O}}_{\text{4}}\right)}_{\text{2}}\left(\text{en}\right)\right]}^{\text{-}}\text{, and }\left(\text{c}\right){\left(\text{Co}\left(\text{EDTA}\right)\right]}^{\text{-}}\text{?}$