Complex sentence: Frasier is determined to show the local audience his brand of therapy can help, and so convinces Roz to call in with a problem which soon develops into helping Roz get over Roger and seems to impress the Spokane audience.
Split into simpler sentences: Frasier is determined to show the local audience his brand of therapy can help, and so convinces Roz to call in with a problem. This soon develops into helping Roz get over Roger, and seems to impress the Spokane audience.