112. Use the comma to separate coördinate clauses that are united by a simple conjunction.
He can sing well, but he seldom will sing in public.
He doesn't wish to sing, and I do not like to urge him.
113. Use the comma to separate the members of a compound sentence when those members are short and closely connected in their thought.
John carried the suit-case, I the hat box, and William the umbrella.
114. Use the comma to separate dependent and conditional clauses introduced by such words as if, when, though, unless the connection be close.
He did not stop, though I called repeatedly.
Your solution is right in method, even if you have made a mistake in the work.
But: You are wrong when you say that.
115. Use the comma to set off short, informal quotations, unless such quotation is a word or phrase closely woven into the sentence.