You compare them to see what is different. sample 1: attacagtactggca sample 2: attacaatactgggca
looking at the sequences carefully you determine it is a mutation.

Fossils of ancestors of the modern horses show a small 4-toed almost dog-like browsing animal named eohippus over time the horses got larger lost toes and changed to a grazing diet what is the best explanation of why this change occurred