Complex sentence: Barrowman resigned from 3i in 1992, to pursue his own business interest in corporate finance, and set up his own corporate finance practice during the 1990s at the age of thirty.
Split into simpler sentences: Barrowman resigned from 3i in 1992, to pursue his own business interest in corporate finance. Barrowman set up his own corporate finance practice during the 1990s at the age of thirty.