I'm using this formula to work out the equation of a line joining points $(1,5)$ and $(-9,2)$:
$ \frac{y-y_1}{y_2-y_1} = \frac{x-x_1}{x_2-x_1}$
Like this:
$ \frac{y-5}{2-5} = \frac{x-1}{-9-1}$
$= \frac{y-5}{-3} = \frac{x-1}{10}$
$= y-5= -3\frac{x-1}{10}$
$= y-5= \frac{-3x-(-3)}{10}$
$= y= \frac{-3x + 3}{10} + 5$
$= y= \frac{-3x + 53}{10}$
$Answer: y= \frac{-3}{10}x + \frac{53}{10}$
My book gives the answer as:
$ y= \frac{3}{10}x + \frac{47}{10}$
I can't see what I'm doing wrong. Any help greatly appreciated.