Nosotros a las diez en punto. empezábamos empezamos

They are both correct, you need more context to determine the correct answer

Explanation:

Empezábamos is the past form of the first person plural from the verb empezar (to begin), while Empezar is the first person present form. Since the rest of the predicate just says "at ten o'clock" you could speak in present or past tense and still make sense.

these are the words to choose from to people answer the question:

nieta--yerno--tia--tio--primo--nuera--abuelo--cunada