Recall the formula for area of a rectangle
A = LW
A = area of rectangle
L = length of rectangle = 6
W = width of rectangle
Also, recall the formula for Perimeter of a rectangle
P = 2L + 2W
P = perimeter of rectangle = 20
We have L=6 and P=20. Use these to solve for W in the perimeter formula.
P = 2L + 2W
20 = 2(6) + 2W
20 = 12 + 2W
8 = 2W
4 = W
Thus, L = 6 and W = 4. Use these measurements to solve for A.
A = LW = 6 * 4 = 24 in^2