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Do you mean that underneath the white ovals there are red ovals? And you want to use the white ones to "cut out" the red ones? If that's what you want, then you need to select both the red and the white. Then do Path menu > Difference.
To do that, the 2 white ovals need to be one single object. So if they are separate, then before you do the Difference, you need to select both white ovals and do Path menu > Union (or Path menu > Combine would work as well, in this case). And if the red ovals are 2 separate objects, you need to do the same thing with those. After that, you can do the Difference.