This document discusses equations and how to solve different types of equations. It begins by defining an equation as a mathematical statement with two expressions separated by an equal sign. It then discusses: 1) The types of equations according to their degree, including linear, quadratic, cubic, and quartic equations. 2) How to solve linear equations by following five steps such as grouping similar terms and reducing. It provides examples of solving various linear equations. 3) How to solve quadratic equations, including incomplete quadratic equations where one or more coefficients are zero, and complete quadratic equations using the quadratic formula. It provides examples of solving different quadratic equations.