Ok, so first you know that the length=3 times the width, or width=x and length=3x.
To find the perimeter of a rectangle, you add the lengths of all the
sides, so you add the width+width+length+length, or x+x+3x+3x.
This is then simplified into Perimeter=8x.
Since the perimeter is 22, you substitute it into the equation:
22=8x
Then, simply solve for x by dividing 22 by 8. The answer is x=2.75.
Since width=x and length=3x, width=2.75 and length=3 (2.75), or length=8.25.
Therefore, the dimensions of the rectangle are width of 2.75 and length of 8.25.
Hope it helps :]