what i need is: 45C, 65M, 60Y, 30K

but my issue is weird. i enter 45, then 65 , 60 and after i enter 30, my cmyk vales goes 0C, 37M, 28Y, 62K

The problem is that Inkscape internally stores all colours as RGB and converts the values you enter into the RGB colorspace. The second problem is that there is no one "correct" CMYK colourspace, and there are multiple ways to convert between RGB and CMYK and back, and the values you enter dont get perserved. In RGB, the colour you want to enter is: #623E47 (I think).

plasticbag wrote:what i need is: 45C, 65M, 60Y, 30K

but my issue is weird. i enter 45, then 65 , 60 and after i enter 30, my cmyk vales goes 0C, 37M, 28Y, 62K

You need to link it to a particular ICC profile.

http://libregraphicsworld.org/blog/entry/getting-cmyk-colors-from-inkscape-to-scribus

May I ask why exactly you need CMYK there?

There's a new extension for getting cmyk for PDF export. Please see this topic: viewtopic.php?f=11&t=5943