Exegesis:

kai ēn ekballōn daimonion ‘and he was driving out a demon,’ without indication of time and place and no connection with what precedes is stated. The clause and the next one describe the event which triggers off the subsequent story.

[kai auto ēn] kōphon ‘and that was dumb,’ i.e. the demon is dumb, and by virtue of that fact the man who is possessed by the demon is also dumb, as the rest of v. 14 shows.

egeneto de ‘and it happened,’ cf. on 1.8.

elalēsen ho kōphos ‘the dumb man began to speak,’ ingressive aorist.

kai ethaumasan hoi ochloi ‘and the crowds were astonished.’ No previous indication of their presence is given.

Translation:

Now, see on 1.57.

Casting out a demon, see on 9.40, and 4.33, 35.

That was dumb, or better to indicate the demon’s function, ‘who made dumb’ (Batak Toba). For dumb, see on 1.22.

The people, or, ‘the multitudes,’ for which see on 3.7. Marvelled, see on “wondered” in 1.21.

Quoted with permission from Reiling, J. and Swellengrebel, J.L. A Handbook on the Gospel of Luke. (UBS Handbook Series). New York: UBS, 1971. For this and other handbooks for translators see here . Make sure to also consult the Handbook on the Gospel of Mark for parallel or similar verses.