Question

how to draw a line from a point if you are given a slope

Answer 1

lets say your at point (0,3)
and you have a slope of -1/3...
slope = rise/run....that means the numerator of the slope either goes up (if positive) or down (if negative). The denominator of the slope goes left (if negative) and right (if positive).

you would start at (0,3) then come down 1, because it is negative, and to the right 3, because it is positive. You would keep coming down 1 and to the right 3 and would eventually cross the x axis.