Answer: Yo soy optimista
I am optimistic
Explanation: The subject in this sentence is "Yo", that is a first-person in the singular, so the verb must be conjugated in this form. Yo soy.

Answer:
Los niños son tuyos y míos.
La casa es de ellos y su pintura es escamosa.
El dinero era realmente suyo para tomarlo.
Finalmente tendremos lo que es legítimamente nuestro.
Su madre se lleva bien con la tuya.
Lo que es mío es tuyo, amigo mío.
El perro es mío.
El gato es tuyo.
Explanation:
Umm... I believe your question is relating to the fact that in Spanish, they use the verb “tener” when talking about age. So if I were to say that I am 3 years old, I would write “Yo tengo tres años”. The verb “tener” means “to have”. In English, we say “I am three years old” not “I have three years old”.