They have very slightly different meanings. Muddle through - to do something or live in a disorganized way, with no plan. Getting by - living and possibly succeeding, but not in a spectacular way. Scrape by - living and making a living, but just barely, with very little extra money, if any. "Just getting by" or "just barely getting by" = "scraping by" Even more dramatic - "Hanging on by my fingernails" = very close to failure or going broke.

muddle along or through = scrape by = make it = manage = cope = get along = get by (informal) = manage somehow They are all the same :)

'"Getting by" and "scraping by" are almost the same. It implies you coped with some problem that was outside of your control. "Scrape by" kinda implies a financial problem. "Muddle through" means something was completed but it was difficult or took a lot of effort. Ex: We don't have much money but we're scraping by/getting by. I only have two good socks but I get by. (scrape by wouldn't sound right here) It took me all night to finish this job but I muddled through it.