math- perimeter with variables

littlebeany99:

What is the length of a rectangle when it is 3 times the width and the perimeter is 96cm?

We know that the perimeter of a rectangle is two times the length plus two times the width.

So 2*length + 2*width = 96

Also, we know that the length of the rectangle is three times the width.

So length = 3*width

So for every length in equation 1 we can write 3*width, this makes;

2*3*width + 2*width = 96 => 8*width = 96 => width = 96/8 = 12

We know length = 3*width so length = 3*width = 3*12 = 36

hope that helped

Always easy when you know how. lol, that's what I'm learning. Just got to get the know how. Nice explanation = logic.