Answer:
lenght= 60 inches
width = 18 inches
Step-by-step explanation:
parameter = 2(L+B)
let lenght be x
width be y
so
x = 3y+6
let's put this in formula
156 = 2( x+y )
156 = 2( 3y+6 + y )
156 = 2 ( 4y + 6 )
156/2 = 4y + 6
78 = 4y + 6
4y = 78-6
4y = 72
y = 72/4
y = 18
so width is 18 inches
and lenght is 3*18+6 = 60 inches
