BY DRAWING THE GRAPH OF y = 3x-3 find where it crosses theY-axis and the
gradient

Find the intercepts:

To draw the graph, plot some points say (0,-3), (1,0) and (2,3),
connect them and get this graph:

 

Now, looking at the graph, answer "How many units must you move your pencil
point vertically along the y-axis from where the line crosses the y-axis
(0,-3) until you get to the origin (0,0)?  Answer: +3 units upward,
(up is +, down is -), so the "rise" is +3

Now answer "How many units must you move your pencil point horizontally 
from the origin (0,0) to get to where the line crosses the x-axis at (1,0)?
Answer: +1 unit right, (right is +, left is -), so the "run" is +1.

The gradient, or slope, is rise/run or +3/+1 = +3

Edwin
AnlytcPhil@aol.com