The ratio of length to width in a rectangle is 3 to 1. if the perimeter of the rectangle is 136 feet what is the length of the rectangle

The width is 1/3 of the length. You can tell that off of the ratio.
To find the perimeter of a rectangle, you have to use the equation:
2L+2W=136
W=1/3L; We can plug that in for W.
2L+2(1/3L)=136
2L+2/3L=136
2 2/3L=136
136÷2 2/3= 51=L
The length is 51 ft. We need to make sure by finding the width and making sure the perimeter is equal to 136.
3:1
51:17
The width is 17 ft. 17+17+51+51
34+102=136
So, the length is 51 ft.