Answer:
The length of the garden is 87 feet
Explanation:
Let
x ----> the length of the rectangular garden
y ----> the width of the rectangular garden
we know that
The perimeter of rectangle is equal to

we have that
The perimeter must be equal to 290 feet
so

----> equation A
The width is exactly 2/3 of the length
----> equation B
solve the system by substitution
substitute equation B in equation A and solve for x

therefore
The length of the garden is 87 feet