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.