Given parameters:
Dimension of the flowerbed = 4ft by 7ft
Unknown:
Number of feet to build the flowerbed = ?
Since the flowerbed will be surrounding the flows, we should simply find the perimeter of the bed.
This is a rectangular area;
Perimeter = 2(L + B)
Input the parameters and solve;
Perimeter = 2 (4 + 7)
Perimeter = 2 x 11 = 22cm
The perimeter of the board is 22cm