Thank you
Call the width, x
Then the length is (1/4)x - 6
Perimeter = 2 [ W + L ]
Perimeter = 2 [ x + (1/4)x - 6]
Perimeter = 2 [ (5/4)x -6]
Perimeter = (10/6)x - 12
Perimeter = (5/2)x - 12
Let Mark's age = t
Four years ago his age was (t - 4)
So we have
t = 8 [ t - 4 ]
