You are taking a photo of a poster on the wall of your dorm room, so you can't back away any farther than 3.1 m to take the shot. the poster is 0.80 m wide and 1.2 m tall, and you want the image to fit in the 15-mm × 22-mm frame of the film in your camera. what is the longest focal length lens that will work? answer in cm with 2 significant figures.