"The chairman is elected by the members."
Translation:Ordföranden väljs av medlemmarna.
"Medlemmarna" is a more litteral translation and it can mean a member in general, not necessary one of the board members. "Ledamöterna" are those participating in board meetings and active in discussions.
What is the difference between väljas and väljs? Apparently väljas was considered a typo in one of those build-a-sentence-using-word-tiles exercises.
väljas is the infinitive form ('to be elected') and väljs is the present tense form ('is elected').
So väljas should have been considered a full mistake, not a typo, but the machinery isn't always perfect.