Question

What is the value of $y$ so that the line through $(3,y)$ and $(2,7)$ is parallel to the line through $(-1,4)$ and $(0,6)?$

Answer 1

Slope of $(0,6)$ and $(-1,4)$ is

$\frac{6-4}{0+1}=\frac{2}{1}=2$

Slope of $(3,y)$ and $(2,7)$

$=\frac{y-7}{3-2}=y-7$

Since the lines are parallel, we have $y-7=2$

$\Rightarrow y=9$.