Answer:
+1/5
Step-by-step explanation:
Answer:
C = commutative property of Addition
12 is the answer because when you add the green and blue you get 5 and 5×4= 20 so you multiply the blue by 4 and the green by 4 and add them together which = 20. so 3×4=12 and 2×4=8 so your answer is again 12
Answer:
Part A) see the explanation
Part B) 
Step-by-step explanation:
Part A)
we know that
A relationship between two variables, x, and C, represent a proportional variation if it can be expressed in the form
or 
Let
C ---> is the total cost (represent the output or dependent variable)
x ----> is the number of books (represent the input or independent variable)
In this problem
we have a proportional relationship between the variables x and C
Part B) we know that
The linear equation is given by

The constant of proportionality k is the same that the slope or unit rate of the linear equation
In this problem the constant k is given

so

For x=12 books
substitute in the equation and solve for C

In function notation
