Length is 3 times the width
So L = 3W
If L is decreased by 4m and with increased by 1m and perimeter is 66 then
2(3W - 4) + 2(W + 1) = 66
6W - 8 + 2W + 2 = 66
8W - 6 = 66
8W = 72
W = 9
L = 3 x 9 = 27
Width of rectangle = 9 m and length = 27 m
New rectangle:
Width is increase by 1 m = 9 + 1 = 10 m
Length is decreased by 4 m = 27 - 4 = 23 m
Answer
Dimensions of new rectangle are 10 m and 23 m