Explanation:
Let x be the length of rectangle and y its width.
P is the perimeter.
So it is given that length is 5 less than twice its width
x=2y-5 so 2y=x+5
also P=2x+2y=26
lets find x
we know 2y=x+5 we replace 2y on P=2x+2y=26
so 26=2x+(x+5)
26=3x+5
21=3x
x=7
so we have that 2y=x+5 so 2y=7+5=12
y=6
we found
length=7
and
width=6