Final answer:
To substitute the direct object pronoun for the name 'los boletos' in the question '¿Dónde compraste los boletos?', you would use the direct object pronoun 'los'.
Step-by-step explanation:
To substitute the direct object pronoun for the name 'los boletos' in the question '¿Dónde compraste los boletos?', you would use the direct object pronoun 'los'. Therefore, the question would be, '¿Dónde los compraste?'
Learn more about Substituting direct object pronouns in Spanish questions