Answer:
The room has a width of three metres, and a length of seven metres.
Step-by-step explanation:
This is solvable using a system of equations. First, we're told that its length is four metres more than its width:
l = w + 4
We're also told that it has a perimeter of 20, and know that the perimeter of a rectangle is equal to two times its length plus two times its length. We can plug the given perimeter into that relationship, giving us:
20 = 2l + 2w
With that, we can simply substitute our first equation into it, replacing l, and then solve for w:
20 = 2l + 2w
20 = 2(w + 4) + 2w
20 = 2w + 8 + 2w
12 = 4w
w = 3
So the width is three metres. We also know that the length is four metres more than that, telling us that it's seven metres.
We can check that my calculating the perimeter with those numbers and making sure it still matches 20
2 * 3 + 2 * 7
= 6 + 14
= 20
so the answer is good.
