Corine collected a total of 11 1/8 pounds of geodes.
Allen collected 5 1/8 pounds of geodes.
Leandra collected 3 3/4 pounds of geodes.
X = Allen + Leandra
X = 9/8 + 3 3/4
X = 9/8 + 15/4
X = (9 + 45) / 8
X = 54/8 = 2 2/8
= 11 1/8 - 8 2/8
= 10 9/8 - 8 2/8
= 2 7/8
So the answer is letter C. 2 7/8