Addition and subtraction of algebraic expressions involves combining or changing the signs of like terms. Division is achieved by using exponent laws to find the quotients of coefficients and variables when dividing a monomial by a monomial. Computation with algebraic expressions follows specific rules for addition, subtraction, and division.

6. Computation with Algebraic Expressions
Addition of algebraic expressions is achieved by combining like terms

7. Subtraction of two algebraic expressions is achieved by changing the sign of every term in the expression which is being subtracted (subtrahend) and adding this result to the other expression (minuend).
Computation with Algebraic Expressions

8. Computation with Algebraic Expressions

9. Computation with Algebraic Expressions

10. Computation with Algebraic Expressions

11. Division of algebraic expressions is achieved by using the division laws of exponents.
1.To divide a monomial by a monomial: Find the quotient of the numerical coefficients, find the quotients of the variables, and multiply these quotients.
Computation with Algebraic Expressions

18. References
http://www.wiziq.com/tutorial/8922-College-Algebra-Lecture-03
www.worldofteaching.com
http://www.intmath.com/Basic-algebra/3_Division-algebra.php