In the Marvel Cinematic Universe (MCU), Tony Stark, also known as Iron Man, is one of the central characters. The character is played by actor Robert Downey Jr. and first appeared in the 2008 film “Iron Man.” Over the years, Tony Stark has appeared in several MCU films, including “The Avengers” (2012).

In “The Avengers,” which takes place after the events of “Iron Man,” Tony Stark is portrayed as being in his late thirties or early forties. However, his exact age is never explicitly stated in the film. It is possible to estimate his age based on information given in other films and interviews with the filmmakers.
According to the MCU timeline, the events of “Iron Man” take place in 2010. In that film, Tony Stark is said to be 35 years old, which would make his year of birth 1975. If we assume that “The Avengers” takes place two years later, in 2012, then Tony would be 37 years old during the events of that film.
It is worth noting that, in the comics, Tony Stark’s age is somewhat fluid and has been retconned several times over the years. However, in the MCU, the filmmakers have attempted to keep the character’s age consistent and have provided some clues as to how old he is at various points in the timeline.
It should also be noted that, while Tony Stark is a fictional character, his age is an important part of his backstory and character development. In the films, Tony is portrayed as a brilliant inventor and billionaire who inherits his father’s company, Stark Industries, at a young age. His youth and prodigious talent are seen as both an advantage and a liability, as he struggles to come to terms with his responsibilities and his own mortality.
Overall, while Tony Stark’s exact age in “The Avengers” is never stated explicitly, it can be estimated based on information given in other films and interviews with the filmmakers. Based on these sources, it seems likely that he is in his late thirties or early forties during the events of that film.