Complex sentence: Under Gannett ownership, WLVI expanded it into a half-hour, 10 p.m. newscast on April 23,1984, the third attempt at a primetime newscast in the Boston market.
Split into simpler sentences: Under Gannett ownership, WLVI expanded it into a half-hour broadcast on April 23,1984. This was the third attempt at a primetime newscast in the Boston market.