Ryan's final exam in math had two parts. He had a total of 60 minutes to complete the entire exam. He spent 20 minutes on Part 1 of the exam. Write and solve an equation to show how much time he had left to complete Part 2.

m − 20 = 60; m = 80 minutes
20 + m = 60; m = 40 minutes
20m = 60; m = 3 minutes
m over 20 equals 60; m = 1,200 minutes