Comma before "then"
Obey your manual of style, either the one you've chosen or the one thrust upon you. I use The Chicago Manual of Style, which recommends that you separate an introductory dependent clause (here, your if) from the main clause.
Obey your manual of style, either the one you've chosen or the one thrust upon you. I use The Chicago Manual of Style, which recommends that you separate an introductory dependent clause (here, your if) from the main clause.