how is the volume of a solution used in calculating concentration?

Start off by finding the slope of the line with the formula
.
Substitute the values. 
Subtract. 
Simplify. 
is the slope of the line.
Now, use the point-slope formula to create an equation, where
is the slope and
is a known point on the line. 
Substitute the values. 
Simplify. 
Move the
to create the final equation in slope-intercept form. 
So if the main question is 9q x 3 it would equal 27q