Differential Equations and Linear Algebra is a free and open textbook introducing the basics of differential equations and linear algebra to undergraduate students. Students should have taken courses in Differential and Integral Calculus before using this textbook. This book is a combination of 3 open educational resources: 1. Elementary Differential Equations by William F. Trench, licensed under CC BY-NC-SA 3.0. 2. Differential Equations for Engineers by Jiří Lebl, licensed under CC BY-NC-SA 3.0. 3. A First Course in Linear Algebra (an open text) by Lyryx Learning – based on original text by Ken Kuttler, licensed under CC BY.