Algebra is a branch of mathematics that simply deals with representing some unknown numbers with letters.
For example;
The area of a rectangle can be written as;
[tex]A=l\times w[/tex]in the above expression, the letter A is used to represent the area of the rectangle, the small letter l is used to represent the length of the rectangle, and the small letter w is used to represent the width of the rectangle.
Adding and subtracting algebraic expressions;
for example: simplify
[tex]2x+3x+5y-2y-x[/tex]we will firstly rearrange the expression and collect the like terms.
[tex]\begin{gathered} 2x+3x-x+5y-2y \\ \text{then we can simplify;} \\ 5x-x+5y-2y \\ 4x+3y \end{gathered}[/tex]Therefore, simplifying the expression above gives.
[tex]4x+3y[/tex]