Final answer:
In Spanish, 'Yo preparo el pastel para ti' means 'I prepare the cake for you', while 'Yo preparo el pastel por ellos' means 'I prepare the cake for them'
Step-by-step explanation:
In sentence 1, 'Yo preparo el pastel para ti' translates to 'I prepare the cake for you' in English. The subject 'yo' refers to 'I' and the preposition 'para' means 'for'.
In sentence 2, 'Yo preparo el pastel por ellos' translates to 'I prepare the cake for them' in English. The preposition 'por' means 'for' and the pronoun 'ellos' means 'them'.
Learn more about Spanish sentence structure