Qué característica en la evolución de las especies se presentó para la aparición del pelo en los organismos terrestres

i think its c. amphipod

the denominator has a very specific role.

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.

: -)