Answer:
L=20 W=8
Step-by-step explanation:
Given the information, we know that L=3w-4 and P=56
The perimeter of a rectangle is always 2L+2w
If we plug what we have into the equation we get
56=2(3w-4)+2w
Distribute
56=6w-8+2w
Simplify
56=8w-8
Add 8 to each side
64=8w
divide both sides by 8
8=w
No that we have the width, we can use it to find our length
L=3(8)-4
L=24-4
L=20