<em>His or her</em> agrees in number with <em>a musician </em>being both singular. However, in order to avoid the akward construction<em> </em><u><em>his or her,</em></u><em> "... musician</em><em>s</em><em> might sell </em><em>their</em><em> instruments..." </em>is a better option.
The sentence is "The man drove away angrily" is in a passive voice, because it that sentence has a verb, that is making the verb stand out. Hope this helps:)