Answer:
1.2 meters.
Step-by-step explanation:
Length of pen = 2x meters
width of pen = x meters
shape of pen is rectangular
we know that area of rectangle is given by length * width
Thus, area of the pen is x*2x = 
It is also given that area of pen is 2.8 square meters.
Equating numerical value of area with area in terms of x, we have

Thus value of x is 1.2 meters.