Your two points are \((-1, 3.2)\) and \((2.6, -8.6)\)
The slope \(m\) is the difference in \(y\) over the difference in \(x\)
So we have
\(m=\frac{(-8.6)-(3.2)}{(2.6)-(-1)}\)
⇒\(m=\frac{-8.6-3.2}{2.6+1}\)
⇒\(m=\frac{-11.8}{3.6}\)
As a fraction, this is \(-\frac{59}{18}\)
As a decimal, this is about -3.27777...
For the y-intercept, you use
\(y=mx+b\)
Plug in the coordinates of one of the points and also the slope
We'll use \((-1, 3.2)\)
\(3.2=-3.2777(-1)+b\)
⇒\(3.2=3.2777+b\)
⇒\(b=-0.07777...\)
which I believe comes out to \(-\frac{7}{90}\)
