From years of studying & drooling over photos such as these where the weights were given, certainly 100 pounds plus each the whole lot of them & depending on the height of the people in the photo to give scale & other variables such as the size of the nerve cavities & whether they're rounded or flattened (unlikely) some of these could easily go 140-150 pounds, beyond that, you would need to be a better guesser than me or to have first hand knowledge of similar sized tusks & there're a dwindling no. of people left alive today who've done so. Such tusks as these are very much a feature of a bygone era.
Steve.