89 Grk “opening his mouth” (a Semitic idiom for beginning to speak in a somewhat formal manner). The participle ἀνοίξας (anoixas) has been translated as a finite verb due to requirements of contemporary English style.
90 Beginning with this scripture. The discussion likely included many of the scriptures Acts has already noted for the reader in earlier speeches. At the least, readers of Acts would know what other scriptures might be meant.

In other versions

Then Philip opened his mouth, and beginning with this Scripture he told him the good news about Jesus.

Then Philip began with that very passage of Scripture and told him the good news about Jesus.

Philip proceeded to tell him the good news about Jesus, beginning with that Scripture.

So beginning with this same Scripture, Philip told him the Good News about Jesus.

So Philip opened his mouth and beginning from this scripture, proclaimed the good news to him about Jesus.

Then Philip opened his mouth, and began at the same scripture, and preached unto him Jesus.

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