A car is travelling at the average speed of $50 \mathrm{km}/\mathrm{hr}$. How much distance would it travel in $12$ minutes?

In a library $136$ copies of a certain book require a shelf-length of $3.4$ meter. How many copies of the same book would occupy a shelf length of $5.1$ meters ?

If the thickness of a pile of $12$ cardboards is $3.5 \mathrm{cm}$, find the thickness of a pile (in $\mathrm{cm}$) of $294$ cardboards.