The length of a rectangular plot is 6m less than thrice it's breadth. Find the dimensions of a plot if it's perimeter is148 m

Dear Student,
Let length of rectangular plot be 'l' m and breadth be 'b' m.
ATQ,
l=3b-6
Perimeter=2(l+b)
148=2(3b-6+b)
4b-6=74
4b=80
b=20 m
So, 
l=3b-6=60-6=54m
Regards!