Equations of a line are often represented in slope-intercept form:
m: slope of the line
(x,y): any point on the line
If you were given two points and asked to solve the system of equations (or find the equation of the line), then you need to solve for m and b.
E.g. using two points on a line: (2, 5) and (3, 7), we have
which you can solve to find
and your solution:
Hopefully that helps...it's basically a long winded way of saying what Irene, Mark & Phillip were hinting at.