Evaluate the needs of each adult in your classroom before you begin instruction, by testing them for their particular level of math knowledge. Unlike a classroom full of children, who are usually mostly at the same level, adults can come into a general math class at vastly different levels of understanding. In order to provide them with math education, you first need to know where each of them is in understanding.
Ask adults about their learning style. It isn't always necessary to develop learning style tests, as you must with children, because adults can answer questions such as "Do I learn better when someone tells me something, or when I read something?" or "Would I rather look at examples to figure something out, or would I rather that someone demonstrate something for me?" If you ask adults to tell you their learning styles ahead of time, you can make sure to plan instruction around those styles.
Plan instruction based on two factors: what the adults need to know, depending on their current math skills, and the learning styles they have.
Listen to the adults in your classroom, and respond to their questions, as well as their comments. Adults don't want to be treated like children, so if they have comments or concerns about the class itself, you can address those. Adults should feel comfortable with you and be willing to give you suggestions for improvement. If they don't, it means that you haven't built up the kind of classroom rapport that makes this possible.