Looks like an MD-80.
The MD-80 is a stretched, uprated DC-9. The MD-80 came from the DC-9-80 upgrade.
The most recent photo in the article is a dc9-50 (has the strakes on the nose, but only one forward cargo door. Md-80 series when views from the side, have (most of the time) a flat duck bill tail cone and 2 forward cargo bay doors. DC-9 series 40 and 50 have strakes or small canards on the nose and dc-9 10,20 and 30 series do not.