Final answer:
The subject pronoun to address two adults in Spanish is ustedes.
Step-by-step explanation:
The subject pronoun that you would use to address two adults in Spanish is ustedes. When addressing more than one person, regardless of their gender, ustedes is the appropriate subject pronoun to use.
For example, if you were speaking to two adults and wanted to say "You are very ambitious", you would say "Ustedes son muy ambiciosos".
It is important to note that while in some Spanish-speaking countries, such as Spain, vosotros is used to address multiple people in an informal setting, in a more formal or respectful context, ustedes is preferred.
Learn more about Subject pronouns in Spanish