What is the perimeter of this rectangle?

From the diagram given in the question, we can get that 
Length of the rectangle = 7 units
Height of the rectangle = 5 units
Then
Perimeter of the rectangle = 2 (Length + height)
                                          = 2 (7 + 5)
                                          = 2 * 12
                                          = 24 units
I hope that the procedure is clear enough for you to understand.