Answer: the fraction of the movie that Chad watched at night is 5/12
Explanation:
Let x represent the fraction of the movie that Chad watched at night.
Chad watched 1/3 of the movie in the morning and he watch some more at night. This means that the fraction of the movie that Chad watched in the morning and at night is 1/3 + x
By the end of the day he still had 1/4 of the movie left to watch. Since the entire movie is taken a 1(whole), it means that
1/3 + x + 1/4 = 1
Cross multiplying by 12(LCM), it becomes
4 + 12x + 3 = 12
4 + 3 + 12x = 12
7 + 12x = 12
12x = 12 - 7 = 5
x = 5/12