In the context of listening to music and doing math, both hemispheres are involved. Listening to music involves processing the auditory information in the temporal lobe, while doing math involves processing the numerical information in the prefrontal cortex. Both of these areas are located in the left hemisphere, but they are connected to each other and to other areas of the brain by a network of neurons. This network allows for the integration of information from both hemispheres, which is necessary for complex tasks such as listening to music and doing math.
So, the answer to your question is yes, right-brained people can listen to music and do math. In fact, all people can listen to music and do math, regardless of which hemisphere they may be more heavily reliant on.