Right answer only i’m giving good points

A River Oaks Pools is trying to calculate the perimeter of the pool so they will know how many bricks to buy for the deck of the pool. Each square on the grid represents a square that is 3ft x 3ft. What is the perimeter of the pool?

Solution:

On the first row and last row, there are 7 numbers of squares. And on the 2nd to 5th row, there are 11 number of squares.

In getting for the perimeter of the area, we'll have to divide the regions. 
Dividing the regions, we'll get three figures/planes :
2 rectangles with Length = 3ft x 4 number of squares and Width = 3ft x 2 number of squares
Thus, for the 2 rectangles,
Perimeter = 2(2L+2W) (times two since there are 2 rectangles)
Perimeter = 2(2(12)+2(6))
Perimeter = 72 ft

Another figure was formed is a square with a 21ft x 21ft
Perimeter = 4(21ft)
Perimeter = 84 ft

Add the two equivalent perimeters:

Total Perimeter = 72+84
Total Perimeter = 156 ft