Formula of Borax is Na2B4O5 (OH)4 · 8H2O.
Hence, x = 5, y = 4, and z = 8.
Therefore, x + y + z = 5 + 4 + 8 = 17.
Method used for separation of mixture of products (B and C) obtained in the following reaction is: 
In the given figure, the blocks $A$, $B$ and $C$ weigh $4\,\text{kg}$, $6\,\text{kg}$ and $8\,\text{kg}$ respectively. The coefficient of sliding friction between any two surfaces is $0.5$. The force $\vec{F}$ required to slide the block $C$ with constant speed is ___ N.
(Given: $g = 10\,\text{m s}^{-2}$) 