To find slope, you follow the slope formula: (y2 - y1)/(x2 - x1)
If you're looking at lines on a graph, you'll want to find 2 points where the line distinctly crosses over the point line and pick that point.
I'll use an example with the 2 point: (3, 12) and (5, 36)
y2 = 36
y1 = 12
36 - 12 = 24
x2 = 5
x1 = 3
5 - 3 = 2
You're left with the fraction: 24/2
Simplify the fraction into 12
Therefore, the slope (or m) is 12.
Slopes can also be fractions, but they would be fractions in simplest form.