First you must know that the sides 2x and x + 8 are equal to each other and sides x and 3x - 16 are equal to each other.
This means you can make a formula like so:
2x = x + 8
and
x = 3x - 16
Now you may solve for x for both of them (you should get the same answer for both x's)
2x - x = (x - x) + 8
x = 8
and
x - 3x = (3x - 3x) - 16
-2x = -16
-2x/-2 = -16/-2
x = 8
To find the length of each side just replace x with 8!
Hope this helped!
~Just a girl in love with Shawn Mendes