Q:

What is the maker and year of this frame with the serial number a2008112

I'm needing help identifying my frame with serial number a2008112 please help

A:

You can easily identify the maker of this bike thanks to the gusset on the frame, it is a Mongoose.

The serial number starts with A, which tells you it was made in January (A : January, B : February, C : March, etc.). 
Then the second character is a 2, which means it was made in 1982 (last number of the year).

So your bike is a 1982 Mongoose.
According to the manufacturing date, it can either be a Supergoose I or II, or a California Special, but I can't really tell with these picture. You would also need to know the frame material to help figuring this out.
If you need more info, hit that link : http://www.vintagemongoose.com/index.php

