length = 7 ft
22 ft = perimeter
Explanation:
Assuming that the piece of wood is a rectangle or a square then the formula to calculate the area would be
length * width = area
Since we are given the width and the area we can plug it into the formula and solve for the length (l)
4 * l = 28 ... divide both sides by 4
l = 7
Now that we have the value of the length we can find the perimeter by using the formula for the perimeter
length + length + width + width = perimeter
7 + 7 + 4 + 4 = perimeter
14 + 8 = perimeter
22 ft = perimeter