To start, you need to define the variables
y-length
x-width
Then write the equation that describe the given situation
y=3x-5 (Eq1)
2x+2y=86 (Eq2)
Clear y from Equation 2
2y=86-2x
y=(86-2x)/2
y=43-x (Eq3)
Equalize equation 1 and 3
3x-5=43-x
Solve x
3x+x=43+5
4x=48
x=48/4
x=12
Use equation 3 to find y
y=43-x
y=43-12
y=31
The length is 31 inches and the width is 12 inches