This book is the third of a series of three Mathematics textbooks for lower secondary level. It closely adheres to the philosophy of the National Curriculum Framework (Secondary), particularly, catering for the 21st century competencies. This book is designed to cater for the needs of students of all abilities. A pedagogically rich approach is used in the presentation of the contents. Furthermore, the focus is on the spiral nature of the curriculum. The present textbook is one of the few textbooks written using a framework called Variation Theory (VT). Variation Theory has been used in the designing of both the contents and exercises. This is done with the intention to help students discern important aspects of the various topics.