"The length of a rectangle is 5/2 units greater than its width"
'greater' here means multiplication, 5/2 units greater or 5/2 times more. So we know that the length is [tex]\sf\dfrac{5}{2}w[/tex].
Perimeter of a rectangle is:
[tex]\sf P=l+w[/tex]
Plug in our value for the length:
[tex]\sf P=\boxed{\sf \dfrac{5}{2}w+w}[/tex]
