Question 178034
I assume the line is straight forward and passes thru whole number coordinates
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if so then you simply take the rise over the run
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in other words the change in the y direction over the change in the x direction ....pay attention to direction
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for example if (1,1) is on the line and you have another point on the line at 
(3,4) ...you count up 1,2,3 units one the y coordinate(positive-if you move down that is negative)and then you move 2 units to the right(positive again-if you move left that is negative).....so you have +3/+2=3/2 slope.  That makes sense because lines with positive slopes rise as you move from left to right and lines with negative slopes fall as you move from left to right.
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hope that answers your question.