New here; advice needed on Jazz Latitude bike

[Qathe]

Hi all, and happy holidays to you. I'm new at biking, again. Someone gave me an old bike that their grandkid is no longer using. It's an adult bike though. It has a little rust, squeaking some, but I have oiled and lubed it as best I know how. The only info on the bike are faded labels for "Jazz" and "Latitude." After Googling it, found it's apparently a mountain bike. I'll be using it to commute about 3 miles (each way) to work and back though, through city streets (small city, suburban Atlanta).

The seat seems fixed, though the people who gave it to me tried to adjust it. Does this bike not have an adjustable seat? It's got the word "Matrix" across the seat so I don't know if it's the original. Rear tire has a completely bald spot on it, no tread at all, so will probably have to replace it at some point.

I'd like to be more knowledgeable about it before I take it in to any local bike shop. What is the usual and expected price range to check it out and adjust for comfort? And price for tire replacement?

Thanks,

Qathe

 

[dabac]

Jazz latitude appears to be a Trek. Even if it's in the lower range, it should be decent enough. The saddle should indeed be adjustable, both in angle and in height. If it has the stock seat post, there's a bolt clamping the saddle to the post. Loosen that bolt, and the saddle will be free to tilt. Height is set by loosening the bolt pinching the top of the seat tube together. Just look at the top end of the tube that the seat post disappears down into.
Unfortunately stuck seat posts is a common problem with bikes that's been sloppily put together, or poorly looked after.
Do a net search for "stuck seat post" and you'll find loads of stories and tips on how to deal with them.
You'll probably not get a fixed price from a shop for breaking free a stuck seat post, as there's no telling how much work it'll be required to break it free.
As for cost, I can't offer much advice. I do just about all my own wrenching, and I'm in a different part of the world. The tire itself can be anything from a 10 USD sales item to a 50+ USD high performance tire. For commuting, I suggest you replace both with fairly skinny (1.5" or somewhat narrower) for a smoother and easier ride. If you're having a shop mount them, buy the tires there too. It'll make the shop happier. Otherwise, I thing Geax Street Runner is a decent budget option.