Answer
$-4.6m$
Work Step by Step
The initial and final centers of mass must be equal. Thus, it follows:
$\frac{m_Jx_{Ji}}{M}= \frac{m_J \times(x_{Ji} + 19 + x_{cf})+m_cx_{cf}}{M}$
We simplify to find:
$x_{cf} = \frac{-19m_J}{m_J+m_c}$
Plugging in 4.8 for $m_J$ and 15 for $m_c$, it follows:
$x_{cf}=-4.6\ m$
