a. To decompose the walkway and find the area, Magdalene could break the walkway down into smaller rectangles and then add up the areas of each rectangle to find the total area. In this case, she could break the walkway down into two rectangles with dimensions of 3 ft by 15 ft and 7 ft by 4 ft. She could then find the area of each rectangle using the formula A = l x w (where A is the area, l is the length, and w is the width) and add them together to get the total area.
b. To find the area of the walkway that Magdalene is replacing, we can use the same method as in part a. The dimensions of the walkway she is replacing are:
3 ft
15 ft
7 ft
3 ft
4 ft
Breaking this down into two rectangles, we get:
Rectangle 1: 3 ft x 15 ft = 45 sq ft
Rectangle 2: 7 ft x 4 ft = 28 sq ft
Adding the areas of these two rectangles together, we get:
45 sq ft + 28 sq ft = 73 sq ft
Therefore, Magdalene is replacing 73 square feet of walkway.