Answer: Ari watched 5/12 of the movie at night.
Step-by-step explanation:
Let x represent the portion of the movie that Ari watched at night.
Ari watched 1 4 of a movie in the morning, and she watched some more at night. It means that the total portion she has watched already is 1/4 + x
The portion of the movie remaining for her to watch is
1 - (1/4 + x) = 1 - (1 + 4x)/4
By the end of the day, she still had 1 3 of the movie left to watch. It means that
1/3 = 1 - (1 + 4x)/4
1/3 = (4 - 1 - 4x)/4
1/3 = (3 - 4x)/4
Cross multiplying by 3, it becomes
1 = 3(3 - 4x)/4
Multiplying through by 4, it becomes
4 = 3(3 - 4x)
4 = 9 - 12x
12x = 9 - 4
12x = 5
x = 5/12
