.the perimeter of a rectangle is 30 m more than three times its width. if the perimeter is 84 m, find the length and width of the rectangle.
width --- w
length --- l
2w + 2l = 84
w+l = 42
3w = 84 - 30
3w = 54
w = 18
l = 42-18 = 24
width = 18, length = 24