Question 727829
The perimeter of the door is all of the sides added together.  Because a door is a rectangle, there are four sides.  Two are the width and two are the length.  We know the width is 3.4 feet and because there are two that is a total of 6.8 feet.  We can use the following equation to solve for the length.  

Length+Length+Width+Width=Perimeter

Length+Length+3.4+3.4=22.8

Length+Length=16

Length=8

The length is 8 feet