You are given the regression line of $y$ on $x$ as $\hat{y} = 3.0x + 2.0$. The sample means are $\bar{x} = 2.0$ and $\bar{y} = 8.0$. If the correlation coefficient is $r = 0.60$, what is the slope $\beta'_1$ of the regression line of $x$ on $y$?