Answer: 
Step-by-step explanation:
Since you did not attach the diagram and I don't know the dimensions of the collage, I will give you a general explanation of the procedure you need to use in order to solve the exercise:
1. You need to use the formula for calculate the area of a rectangle:

Where "l" is the length and "w" is the width.
2. Using the formula, you must calculate the area of an small picture.
You know that its length is 4.5 inches and its width is 3.5 inches. Therefore, its area is:

3. Calculate the area of the collage using the formula:

4. Finally, divide the area of the collage by the area of an small picture in order to find the number of small pictures that will fit within the collage:
