Newbie Issues - Chamfer Edges

[Psionw35]

Apologies in advance but I am very new to 3D design and this is my first attempt at creating a project.

I am trying to chamfer the bottom edges of my design but cannot seem to get it how I want it. I want the chamfer to start 43mm in from the edge of the bottom and round to 35mm from the top edge on the front.

Any guidance would be greatly appreciated.

Thanks

[Oregonerd]

Can you mark up the image to help us see what you want? Coffee is just kicking in…