I would do the same thing I recommended in this thread: https://www.excelforum.com/excel-gen...wo-points.html

1) Extract known values/entries into a second table. This table will be used as a lookup table for the linear interpolation.
2) Compute slope/intercept for each pair of points in the lookup table.
3) Use lookup functions to get slope and intercept for each point in the main table and compute interpolated values.

Which step or steps do you get stuck on?