SOLUTION: Please help with this, my exam is tomorrow. Thanks A picture frame has the perimeter of 40 inches. If the width is 4 inches shorter than the length, what are the length and widt

Algebra ->  Coordinate Systems and Linear Equations  -> Linear Equations and Systems Word Problems -> SOLUTION: Please help with this, my exam is tomorrow. Thanks A picture frame has the perimeter of 40 inches. If the width is 4 inches shorter than the length, what are the length and widt      Log On


   

Question 752953: Please help with this, my exam is tomorrow. Thanks
A picture frame has the perimeter of 40 inches. If the width is 4 inches shorter than the length, what are the length and width?
I set it up like this but its not making any sense to me. 2(2w)-2l=40 my answer key says L=12 and W=8
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
The formula for the perimeter is
+P+=+2W+%2B+2L+
You are given that +W+=+L+-+4+
and +P+=+40+ in
----------------
By substitution:
+40+=+2%2A%28+L+-+4+%29+%2B+2L+
+40+=+2L+-+8+%2B+2L+
+40+%2B+8+=+4L+
+4L+=+48+
+L+=+12+
and, since
+W+=+L+-+4+
+W+=+12+-+4+
+W+=+8+
The length is 12 in and
the width is 8 in