Write an equation of the line in slope-intercept form, the line passing through $(-1, 3)$ and $(-4, 5)$. I know that $y=mx + b$ and the slope is $2/3$ but when I plug in the points $3=\frac23 (-1)+b$ to find $b$, I keep getting answers that don't make sense. Graphing hasn't helped either. Just wondering what I am doing wrong.
The slope $m$ is calculated as follows:
$m = (y_2 - y_1) / (x_2 - x_1) = (5 - 3) / (-4 - (-1)) = -2/3$, not $2/3$.
Then you can substitute one of the point's values and $m$ to find $b$.
$y = mx + b$
$5 = -2/3(-4) + b$
$5 = 8/3 + b$
$b = 7/3$