Is this possible to draw rectangle using Fixed Ratio based on the product...?

Hi Everyone,

Is this possible to draw rectangle selection using Fixed Ratio("2:3" or "4:5") based on the product...?

I have T-Shirt image on the background and I need to draw rectangle using Fixed Ratio based on the Tshirt.

Note: I get Height and Width of T-shirt which is from Overall T-shirt Path

Anyone Please guide me to complete this task. Thanks in advance.

-yajiv