Let c and b be the costing of each cobble and burrey in slugs respectively. We have :

\(\left\{{}\begin{matrix}2c+3b=19\\37-5c=4b\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}10c+15b=95\\10c+8b=74\end{matrix}\right.\)\(\Rightarrow\left\{{}\begin{matrix}7b=21\\c=\dfrac{19-3b}{2}\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}b=3\\c=5\end{matrix}\right.\)\(\Rightarrow b+c=8\)

So,the answer is 8 slugs.

So, 1 cobble and 1 burre