How related are whale, dolphins and porpoises to cows?Was the extinct quagga more like a zebra or a horse?

Molecular evolution and phylogeny
At the molecular level, evolution is a process of mutation with selection. Molecular evolution is the study of changes in genes and proteins throughout different branches of the tree of life.
Phylogeny is the field of study of the inference of evolutionary relationships. Phylogeny is
centered on the use of tree-like diagrams to represent evolutionary pedigrees. Traditionally, phylogeny relied on the comparison of morphological features between organisms. Today, molecular sequence data are also used for phylogenetic analyses. Molecular phylogeny is based on sequences and the comparison of sequences. Multiple sequence alignment is crucial to molecular phylogeny.
Goals of molecular phylogeny:
A TRUE TREE depicts the actual historical events that occurred in evolution. However, it is essentially impossible to generate a true tree. Instead, we generate inferred trees, which depict a hypothesized version of historical events.
Some major goals of molecular phylogeny are to deduce correct trees for all species and to
estimate times of species divergence. Here are some questions that molecular phylogeny may help answer:
(i) How many genes are related to my favorite gene?
(ii) How related are whale, dolphins and porpoises to cows?
(iii) When and where did HIV and other viruses originate?
(iv) What is the history of life on earth?
(v) Was the extinct quagga more like a zebra or a horse?