I recently was in a accident and the other's guy insurance said something about 80/20 law even though thhe guy who hit me said it was his fault and the adjuster said they will only pay 80% of the damage and on top of that they won't cover the towing and storage bill. Wha can I do about it?

if this is the other persons insurance, tell them bull, and tell them, that you guess they want to pay your lawyers bill also.

Adjusters try to pay the less they can. Unless the police report shows both at fault, the person at fault will pay all claims

... the other's guy insurance said something about 80/20 law ...

It might be some law in your jurisdiction about 20% comparative negligence. But without knowing which state or country you are in, that would only be a guess.