What is the slope of a line parallel to $y-axis$?

Find the equation of the line which cuts the intercept of $6 \mathrm{units}$ from $y-axis$ and whose slope is $\frac{-5}{3}$.

Find the equation of the line which passes through the point $\left(6,0\right)$ and whose slope is $\frac{7}{3}$.

Find the slope of the line which passes through the origin and also passes through the point $(2,3)$.