I’m not sure if this may be to hard of a method for you depending on which grade you are in but I’ll try and explain the best I can.
Use the formula:
Y2 - Y1
————
X2 - X1
Take two points from the line: (10,30) and (40,50)
Only because they have exact values
(10,30) and (40,50)
The 10 is X1 because it’s the x of the first coordinate. 30 is Y1 for the same reason
The 40 is X2 because it’s the X of the second coordinate. 50 is the Y2 for the same reason
Substitute this into the formula
50-30
———-
40-10
= 20
—-
30
Which simplifies to 2
—
3
So the slope of the line is 2
—
3
I hope this helps.