35 / 5 = 7 ; also 49 /7 = 7
So
? = 8 x 7 = 56
Answer
Missing side length = 56
Unfortunately, there are no given choices. However, I could provide the possible inequalities from the given problem. Converting the given to inequalities:
3.2x + 0.8y < 50
x + y = maximum
There is no other limiting equation (i.e. the total cost of the books) such that the, if you wanted to maximize x, results to minimum y and vice versa.
The volume of the sphere is 
Explanation:
Given that the diameter of the toy ball is 12.5 inches
We need to determine the volume of the toy ball.
The radius of the toy ball is given by



Thus, the radius of the toy ball is 6.25 in
The volume of the sphere can be determined using the formula,

Substituting the values, we get,

Multiplying, we get,

Substituting
, we have,

Simplifying, we get,

Thus, the volume of the sphere is 