Answer:
28
Step-by-step explanation:

as you notice above, is the first-row components from A, multiplying all the columns subsequently on B, and you add the products of that row, that gives you one component on the AB matrix
in the one above, we end up with a 2x3 AB matrix
Graph A since it crosses all 4 regions of the graph
To divide by a fraction, multiply by the reciprocal of that fraction.
1/3 • 5/1 or 1/3 • 5
Calculate the product straight across.
1/3 • 5/1 = 5/3
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
