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

Answer:
5 (-9x)
Step-by-step explanation:
Product of 5
5 * ()
difference of 9
5 * (-9)
and a number
5 * (-9x)
Answer:
b
Step-by-step explanation:
Answer:
Carla has been running 7 miles each day for 13 days.
Step-by-step explanation:
Carla ran 3 miles on her first day, 5 miles on her second day and then 7 miles each day onward.
Let the number of days she ran 7 miles each day = x
Total distance run by Carla = 3 + 5 + 7(x)
= 8 + 7x
If her log book shows that she has run total distance = 99 miles
Equation representing her total run will be,
8 + 7x = 99
7x = 99 - 8
7x = 91
x = 
x = 13 days
Therefore, Carla has been running 7 miles each day for 13 days.