We are given area of the ribbon = 144 square inches.
We know formula for side of a square =
.
Plugging value of area in the formula, we get
Side of the square

= 12 inches.
Sonya wants to sew ribbon along each side of a square pillow.
So, we need to find the perimeter of the square pillow.
Perimeter = 4 × side = 4 × 12 = 48 inches.
Therefore, she buy 48 inches of ribbon to have the exact amount that she needs.