Processes and Segmentation
I am guessing that overheads P, S, and T exclude per page/segment overheads and are per-process overheads (if they are per-system overheads, the adjustments are obvious), so the overhead of each process would be P + page_count * 4 bytes for paging, S + segment_count * 8 bytes for segmentation, and T + segment_count * 8 bytes + page_count * 4 bytes for segmentation and paging.

(The inclusion of a maximum segment size is confusing since insufficient information is provided to determine if any of the 8 segments in process P4 are larger than 256 KB, though at most one segment can be.  Since the mean segment size is significantly less than the maximum allowed size, I just assume that no segment needs to use two segment table entries.)

It might help clarify the equations to substitute A &lt; B &lt; C with A = B + k1 = C + k1 + k2 (where k1 and k2 are greater than zero).  It should then be straightforward to determine what values of k1 and k2 are needed for equality and so derive the conditions under which each memory management method has greater overhead (with negative values for k1 or k2, of course, being impossible).