The evolution of the eohippus into the modern day horse is an example of a. character change b. stasis c. extinction d. metamorphosis

it is actually character change

try using substitution:

x + y - 6 = x - y. (i'm not giving you the exact answer). since 0 = x - y, then sub 0 in the equation with x - y. combine your like terms, and then use inverse operations, and you'll have your answer.

: -)