find slope regression of a line

The slope of a regression line (b) represents the rate of change in y as x changes. Because y is dependent on x, the slope describes the predicted values of y given x. When using the ordinary least squares method, one of the most common linear regressions, slope, is found by calculating b as the covariance of x and y, divided by the sum of squares (variance) of x, 

Remember from algebra, that the slope is the “m” in the formula y = mx + b.
In the linear regression formula, the slope is the a in the equation y’ = b + ax.

:D