Antonyms for the phrase "be in a quandary" could include "be decisive," "be certain," "be sure," "be resolved," or "be determined." When someone is in a quandary, they typically feel confused, uncertain, and hesitant about what to do next. Therefore, antonyms for this phrase would be words that convey a sense of clarity, confidence, and conviction. For instance, if someone is faced with a difficult decision, they could choose to be decisive by considering their options carefully and making a confident choice. Alternatively, they might be sure of what they want and be resolved to pursue it, regardless of any obstacles that may arise.