Well, the formula for the perimeter of a rectangle is:
2l + 2w.
So, by plugging in our values of the length and width, we can easily find an answer:
length = L
width = 1 + L ( 1/3 )
2 ( L ) + 2 ( L ( 1/3 + 1 ) = 42
2l + 2/3( L ) + 2 = 42
8/3 ( L ) = 40
L = 40 * 3/8
L = 15
Therefore, the length is 15 and the width is 6.