# Pre-Algebra Examples

,
Use to calculate the equation of the line, where represents the slope and represents the y-intercept.
To calculate the equation of the line, use the format.
Slope is equal to the change in over the change in , or rise over run.
The change in is equal to the difference in x-coordinates (also called run), and the change in is equal to the difference in y-coordinates (also called rise).
Substitute in the values of and into the equation to find the slope.
Finding the slope .
Simplify the numerator.
Multiply by .
Subtract from .
Simplify the denominator.
Multiply by .
Divide by .
Find the value of using the formula for the equation of a line.
Use the formula for the equation of a line to find .
Substitute the value of into the equation.
Substitute the value of into the equation.
Substitute the value of into the equation.
Find the value of .
Rewrite the equation as .
Simplify the left side.
Multiply by .