I want to know the answer to the following question:
Which French mathematician expanded on earlier work of Paolo Ruffini and Joseph-Louis Lagrange?
All the background I'm provided with is that "The 19th-century French mathematician Évariste Galois, extending prior work of Paolo Ruffini and Joseph-Louis Lagrange, gave a criterion for the solvability of a particular polynomial equation in terms of the symmetry group of its roots (solutions).". Is that enough to answer the question?