to find the slope if you have a graph, start with the bottom point and count up until you meet up with the same line as the second point.
Now count across to the second point.
You will write these numbers as a fraction: - 4/6
The number you count up is the numerator(top number) and the number you count across is the denominator(bottom number).
Now if the line goes down from left to right, then the slope with be negative(-). If the line goes up from left to right, then the slope is positive(+)
I hope this helps.