Answer:
D
Step-by-step explanation:
Let's call the width of the yard x and the length x + 3½. Since we know that perimeter = 2 * (width + length) and that the perimeter must be 26 we can write:
2 * (x + x + 3½) = 26
x + x + 3½ = 13
2x + 3½ = 13
2x = 9½
x = 4