An important but problematic component of nuclear geophysical technologies is computer inversion of measurement data based on the equation of particle transport. In this paper, we propose an approach and iterative methods for this inversion that are applicable to many problems of evaluation formation characteristics, including elemental composition, from data of corresponding logging methods. This approach is based on defining characteristic elements, interactions, and trajectories and using the superposition principle for transport processes, and linear a priori constraints on unknowns are used. In comparison with the previous publications of the author, this paper deals with a broader type of measurement data, including the reading ratio of detectors and normalized measurements. The iterative methods are specified for problems of determining the porosity and density from data of neutron-neutron and gamma-gamma logs, respectively. For the first of them, the results of numerical experiments are presented.