Mi hermano y yo llegamos a la casa de __ padres.. nuestra. nuestros. sus. tu. mónica necesita __ mochila.. mis. nuestro. su. sus. ramón busca __ cuadernos.. mis. nuestra. sus. tu. yo llamo por teléfono (call on the phone) a __ amiga.. mi. mis. su. tus. tú regresas a __ apartamento.. nuestros. su. tu. tus

The first answer is nuestros. "Mi hermano y yo" means "My brother and I," which correlates to the first-person plural (we). "Sus" means "their" and "tu" means "your," while "nuestra" and "nuestros" means "our." The ending of nuestra or nuestros will then depend on the word it's describing "padres" (parents). "Padres" is masculine and plural, so the ending will be -os for nuestros. The second answer is "sus." This is because Ramon corresponds to masculine singular (he), which relates to "sus." "Sus" is plural because the word it's describing, "cuadernos" (notebooks) is also plural. The third answer is "tu." "Tu" (you) is second person singular, which corresponds with "tu" (your). "Tu" remains singular because "apartamento" (apartment) is also singular.