X=4
First find the solution to (x+1) ft. I chose to guess the answer as 4 and it worked (you’ll have to guess). I then plugged 4 into the other equation 2x. It became 2•4. Solving give the side length of 8 ft. Then you have to check to make sure they both have the same area. To do this just solve the equations.
First rectangle- 4•4= 16 ft area
Second rectangle- 2•8 = 16 ft area
( I’m really sorry if this is confusing)