A free original bilingual lesson for the Ratios Percentages and Commercial Comparisons module of RRB Group D Mathematics. Name the compared quantities, preserve their order, match units and simplify ratios. Use equal ratios to find missing terms; recover shares from a total, known part or difference; and join ratios through a shared quantity. Entry checks, coached examples, an analogy, a quick reference and 12 practice questions with explained answers support learning. This PDF covers this topic only, not the complete Mathematics syllabus or a full CBT simulation.