Check the 4 digit number stamped on the head badge. First three numbers are the date, last number is the year (ex: 1008 = 100th day of 78 / 88 / etc). Since your bike does not have indexed shifting, I'm guessing your bike to be around 87-88ish. It was manufactured by Giant, and was 3rd from the bottom in the model line. It came with a lugged steel frame, alloy rims w/ F.QR, and ok components. Decent enough bike for $25.

GregG