Answer: tuya
Tu mochila es tuya.
Your backpack is yours.
Explanation: In Spanish the pronouns have to agree in gender and number with the object they replace. "Mochila" is a feminine and singular noun, so its pronoun also has to be feminine and singular. In addition, since the standard second-person possessive adjective "tu" is used before the noun, we must use the standard second-person possessive pronoun in this sentence. "Tuya" means yours.
