How do you do linear equations with points on a graph?

Answer 1

That will depend on the given straight line equation and then by plotting the x and y values on a graph the result will be a straight line that may be positive, negative, parallel to the x axis or parallel to the y axis.

Answer 2

Suppose A = (a, b) and B = (c, d) are two points on a straight line. Then the equation of the line is
(x - a)*(d - b) = (y - b)*(c - a)

or, equivalently,

x(d - b) - y(c - a) - ad bc = 0