Without any more information, you question is almost impossible to answer with any real degree of accuracy. Value will depend on where you live, how bad you want to sell it, condition, finish, accessories, box, papers, engraving, what choke it is, barrel length, detailed description of all markings, stock wood, etc.. You could be in the 100-1000 USD or more range.
50-500 usd
$250-500 depending on condition
Download a manual from Browning or take it to a gunsmith
Best to ask a gunsmith for help.
Yes, Browning made the B80.
Your Browning B-80 in the description you described is valued at 450 dollars.
$250-500 depending on condition
100-400 USD
Not sure if it is a B80 or an A500, but it was made in 1988 in Europe (not Japan). Depending on which model, $400-$500.
1985
Depending on condition, from 250-450 USD.
1981