Crack in Foundation and floors slope both sides (slab foundation)

Hi All,
I'm starting my house hacking journey with single family (not good multi families in the area!) and I found the house to have a crack in the foundation. It has a crown in the middle and the floors are sloping both ways. Is this typical for a house of 60 years old with a slab foundation? Would it affect renting or resale value? If it is safe, how do I negotiate with the seller for a lower price (Can I ask 10-20% reduction?). Really appreciate your inputs on this. Thank you in advance!