Do not rely on existing solution sets for grading. Many circulating copies are wrong on group actions and ring homomorphisms.
Pinter’s book is excellent; the unofficial solutions are mediocre at best . Use them sparingly and skeptically. a book of abstract algebra pinter solutions
Do exercises without solutions first. Use Math Stack Exchange (search “Pinter exercise [chapter] [number]”) for hints or verification. Avoid bulk solution PDFs – they contain enough errors to mislead you. If you must have a full answer key, try to find one vetted by a professor or TA. Do not rely on existing solution sets for grading