This is a set 5 problems of different types and a few are not easy. All are solved in mind using concepts and techniques such as, pattern discovery, componendo dividendo, missing element technique, similarity increase technique, denominator equalization, dummy variable substitution, abstraction, three variable zero sum principle, algebraic ratios, basic ratio concepts, working backwards approach, and mathematical reasoning. The Concepts and Techniques, explained with precision and details, form the BASIC SKILLSET for solving harder algebra problems EASILY IN MIND...