Question 47170
This is a classic word problem. Best done via algebra, as follows.
Let l be the length of the rectangle, and w be the width.
So, we have two equations, that is,
eqn1: l = 2w + 4
eqn2: l + l + w + w = 26.

Finding the equations is supposed to be the hard step, now we try to solve it. Substitute eqn1 into eqn2 to get
(2w+4) + (2w+4) + w + w = 26
which simplifies to
6w + 8 = 26
which means w = 18/6 = 3.
which means l = 2x3 + 4 = 10.