Should I buy this hybrid cycle?
 

I found a used fuji absolute 4.0 2011 for a decent price,is it good enough for 30-50km rides?The original bike is equipped with Shimano tourney but the used one has Shimano acera but the bike was in good condition overall? I need your opinion should i get it?

yes, and then start riding

If the gears work, the chain doesn't skip on the small cog, the bike fits, the brakes work, there are no cracks or big dents, and the wheels turn nicely, and the rest of it looks safe to ride, then sure, get it (if the price is right) and welcome to the sport / pastime / mode-of-transportation.

If you immediately spot several things that need replacing; tires, brake pads, rear cassette (chain skips), those can add up fast, and you should budget accordingly.

Any bike that fits you well, that has gearing that will match your type of terrain and fitness level, and that is in good working order will suffice for 25km - 50km rides. The limiting factor will be your body's level of adaptation to spending hours in the saddle. To that end, start with 10k rides and work your way up until you reach your distance goal.

Yes.

I've consulted the Magic 8 Ball:
"Cannot predict now"

"a decent price" How much is that? This is a good starter bike, but if you already do regular 30-50 km rides you may soon outgrow it. This would be the sort of bike someone might buy as a beginner, but by the time they reached the point where they were doing 50 km rides they would move on to something better. This is an 8 year old bike that should probably sell for about $100 if it is excellent condition. Is it a good frame size for you? For a 30-50 km ride, fit is very important, you will be sitting on the bike for hours at a time.
This appears to be your first post. Most people answering don't wish to talk down to you, but we have no way to know about your own experience with cycling. If you assume that we know what you mean by the price of the bike in question being reasonable without a dollar amount, we can easily misunderstand each other.

All depends on the color

If the decent price is well under $100 and the bike is in excellent shape and doesn't need anything at all then possibly. Other than that I would take a pretty hard pass. The first number in the Fuji designation refers to frame quality so a 1 is good and a 4 is generally the lowest they go.

That possibly refers to the bike fitting you well and also being comfortable for you. Also it refers to how much you plan on riding. If you are riding once and a while and not because your bike is heavy or slow or doesn't shift or brake well type of stuff that is common with that type of riding, then sure it could be an OK bike for that. However if you are looking to put in the miles or kms in your case then a cheaper used bike might not be the move especially since you will have zero warranty with it and no aftercare (unless the previous owner is really knowledgable about fixing bikes and is also really nice and willing to do it which is rare). Also if you are looking to ride a lot, typically cheaper bikes don't have a great ride quality and certainly shifting and likely braking won't be great. Sure it has been minorly upgraded to Acera in this case but that still isn't great and especially over time it doesn't keep well.

Ride some bikes and find one that really works well for you and be careful of just settling if you aren't sure of what you want or if the bike will work for you. Price generally should be towards the bottom of the list when finding a bike because you don't save any money if you have a bike that isn't what you want or need and I see and hear about plenty of bikes that get neglected or underused because the owners pretty much solely focused on price and didn't get what they really wanted. I am however not saying you have to spend tons and tons of money but you want to spend enough to get something you will be happy with months and years down the line and will still function decently with proper upkeep and minimal money put into non-general wear items. Buying chains, cassettes, cables/housing, brake pads and rubber is fine but if you have to replace derailleurs and shifters and calipers and wheels a lot that is not good.

Frankly, my biggest concern is the upgraded rear derailleur. Why was that done?

If you can test ride it and it shifts okay both up and down, I'd probably go for it.

Oh - and whatever the asking price, negotiate.