How do I Find the slope of the line passing the points 3 and -9 and 7 and 6?

The slope is the change in y divided by the change in x ("rise over run").

For the points (x1, y1) and (x2, y2), the slope calculation is:

( y1 - y2 )

( x1 - x2 )

For the points (3, -9) and (7, 6), the slope calculation is:

( -9 - 6 ) = ( -15 ) = 3.75

( 3 - 7 ) ( -4 )