Two cubes each of volume 64 cm³ are joined end to end, then the surface area of the resulting cubiod is

Volume of each cube  $=64{\mathrm{cm}}^3$
$\begin{array}{l}{\mathrm{a}}^3=64\\ \mathrm{a}=4\end{array}$
Side of each cube $=4\mathrm{cm}$ 
After joined end to cuboid will be formed 
$\mathrm{\ell }=8\mathrm{cm},\mathrm{b}=4\mathrm{cm},\mathrm{h}=4\mathrm{cm}$
Surface area of resulting cuboid $=2(\mathrm{\ell b}+\mathrm{bh}+\mathrm{\ell h})$ 
$\begin{array}{l}=2(32+16+32)\\ =160{\mathrm{cm}}^2\end{array}$