Why not "mare"?
Adjectives need to agree in gender and number with the noun. "Găinile" is plural, but "mare" is singular.
Ah, thank you, I thought it was plural feminine. :)
What is the difference between the given answer and "Puii sunt mari și grasi?"
Not much, except that "puii" means "the chickens" and "găinele" means "the hens".
why not gainii?