**Important Concepts and Formulas**

1. An equation is a statement of
equality between two expressions involving variables and constants.

2. An equation has two sides separated
by the symbol (=). The two sides are LHS and RHS.

3. Linear expressions are those in which
the highest power of the variable is 1.

4. Linear equation in one variable is of
the form ax + b = c, where a, b and c are constants and a ≠ 0.

5. The value of the variable, which
makes both sides of the equation same is called the solution of the equation.
For example, x = 3 is the solution of equation 4x – 5 = 7.

6. If LHS and RHS are interchanged, the
equation remains the same.

7. Methods of solving linear equations
in one variable:

·
Add
the same term (constant and/or variable) to both sides of an equation.

·
Subtract
the same term (constant and/or variable) from both sides.

·
Multiply
both sides by the same term (constant and/or variable).

·
Divide
both sides by the same term (constant and/or variable).

8. You can use the general strategy to
solve word problems as follows:

·
Read
the question carefully and identify the unknown quantity.

·
Use
a letter x to represent the unknown quantity.

·
Express
other quantities in terms of x.

·
Form
an equation based on the given information.

·
Solve
the equation.

·
Write
down the answer statement.