Hi!
Because this is a parallelogram, we know that AB is equal to CD.
2x + 1 = x+13
Now solve by isolating x on one side.
Subtract 1 from both sides.
2x + 1 - 1 = x + 13 - 1
2x = x + 12
Subtract x from both sides.
2x - x = x - x + 12
x = 12
The answer is x = 12
Hope this helps! :)
-Peredhel
