Answer:
She will need 22 feet of ribbon
Explanation:
The length of the border of ribbon is equal to the perimeter of the rectangular picnic blanket
The formula of the perimeter of a rectangle is P = 2(l + w), where l is its length and w is its width
∵ The long side of the blanket is 7 feet
∴ l = 7
∵ The short side of it is 4 feet
∴ w = 4
Use the formula of the perimeter above to find the perimeter of the blanket
∵ P = 2(l + w)
∴ P = 2(7 + 4)
- Add the numbers in the bracket
∴ P = 2(11)
∴ P = 22 feet
∵ The length of the border of ribbon is equal to the perimeter
of the blanket
∴ The length of the ribbon is 22 feet
∴ She will need 22 feet of ribbon