To determine the length of the stones he will need to go around his patio, Lorenzo will need to find the perimeter of the patio.
To find the perimeter, you will need to know the length and the width of the rectangle.
The width us 12 feet, and the length is 14 feet (12 +2).
P = 2l +2w
2 x 14 + 2 x 12
P = 52 feet
Lorenzo will need at least 52 feet of stone to go around his patio.