Answer:
the volume of sand is 
Step-by-step explanation:
This problem bothers on the mensuration of solid shapes, rectangular prism.
Given data

if the sandbox is filled with sand of
deep the volume of the sand in the box will be calculated based on the the depth of the sand
converting the depth of sand from mixed fraction to proper fraction we have 
the expression for the volume of a rectangular prism is

substituting our data into the expression we have

to find the area of the figure, you first need to find the area of the separate figures: a triangle and a square.
first, find the area of the triangle:
multiply 13 and 5 to get 65.
divide 65 by 2.
32.5.
then, find the area of the rectangle:
multiply 5 and 14 to get 70.
add those answers up, and you get:
102.5
These are what you can plot:
(-2, 0.444), (-1, 0.667), (0,1), (1, 1.5,), (2,2.25)
I believe the answer is 2.222222222