Identify 1980's Bianchi?
The bike might be the a 1981 Rekord "W" Strada, at least this catalog page shows a very similar photo, but no exact parts list:

It might also be another Bianchi mixte-style frame with components swapped, i.e. flat bar to drop bar, which makes identification harder.

Or it might be a late '80s (possibly 1986) womens Bianchi Strada, as shown in this question. Note that serial numbers on both bikes are very close: 51027534 vs 51027563.