Let's say the width is x. If the length is 3 meters more than the width, the the length is x+3.
A rectangle has 4 sides. 2 widths and 2 lengths. If the perimeter is 26 meters, you can plug in your expressions for the width and the length to solve for x.
2(x+3) +2(x)=26
2x+6+2x=26
4x+6=26
4x=20
x=5.
If x=5, that means that your with is 5 meters, and your length is 8 meters (5+3)
