Use the linear regression feature of a graphing calculator to calculate the equation of a line given the following two points that the line passes through: (12, 8) and (14, -6).
Using Linear Regression is overkill, but here's how I would do it on a TI-89.
Press APPS.
Select Stats/List Editor.
In List1[1], input 12
In List1[2], input 14
In List2[1], input 8
In List2[2], input -6
Now F4 (Calc) -> Regressions -> LinReg(ax+b)
Then input as follows (Press 2ND: VAR-LINK to search for the lists):
X List: List1
Y List: List2
Store RegEqn to: y1(x)
Then press ENTER one or two times.
You should get