SOLUTION: Hi. This is the problem I have: The length of a rectangle is 3 times its width. If its perimeter is 32m, what is its area? My friend has only written down on my book: 3x4=12

Algebra ->  Rectangles -> SOLUTION: Hi. This is the problem I have: The length of a rectangle is 3 times its width. If its perimeter is 32m, what is its area? My friend has only written down on my book: 3x4=12      Log On


   

Question 915411: Hi. This is the problem I have:
The length of a rectangle is 3 times its width. If its perimeter is 32m, what is its area?
My friend has only written down on my book:
3x4=12
12+12+4+4=32 and
12x4=48
I don't understand how she got these numbers and would like you to explain this to me.
Thank you.
Answer by josgarithmetic(39625) About Me  (Show Source):
You can put this solution on YOUR website!
w for width, L for length;
L=3w;
and
2w+2L=32;
and you want to know area, which is wL.

Substitute for L in 2w+2L=32.
2w%2B2%283w%29=32
w%2B3w=16
4w=16
w=16%2F4
w=4
Use the now found value for w to compute or evaluate L.
L=3w
L=3%2A4
L=12
-
You now know both w=4 and L=12, and you can compute the area, w*L.