Step-by-step explanation:

Surface area is the area of the faces added together.
First lets find the area of one of the triangles.
Area of triangle is 1/2*base*hight
Area=1/2*2*3= 3
Area of ONE tringle is 3, and area of the FOUR tringles is 4*3 whihc is 12
Now lets find area of square
area of square is side*side
So, area is 2*2 which is 4
Now lets add area of triangles+area of square
12+4 which 16
Surface area is 16
Graphing is a good method when you have small integers or fractions as your slope.
Substitution is a good method when you have two equations, and when one of the coefficient of the variables is one.
Linear combinations is a good method when you have the same coefficient for the same variable in 2 different equations.
B, that’s easy... Just add them up.
Answer:
A. 
Step-by-step explanation:
We are given,
The cost of one book = $2.25
Since, it takes $2.25 to buy 1 book.
The, for $10, we can get
i.e.
= 4.44
Since, number of books cannot be in decimals.
So, the closest integer to 4.44 is 4.
Hence, we can buy 4 books from $10.
Now, according to the options:
A. 
B. 
C. 
D. 
Hence, we see that from the options, A is correct.