# Question #e94ae

$6$ metres.

#### Explanation:

Preparing a $1$ metre wall costs $\rightarrow$ Rs. $1.35$

So, It will cost Rs. $340.20$ to prepare walls of total $\frac{340.2}{1.35}$ ${m}^{2}$ = $252$ ${m}^{2}$

So, The total area of the walls = $252$ ${m}^{2}$

And It costs Rs. $0.85$ for matting a floor of $1$ ${m}^{2}$.

So, It costs Rs. $91.8$ for matting a floor of $\frac{91.8}{0.85}$ ${m}^{2}$ = $108$ ${m}^{2}$

We are given the length of the room is = $12$ metres.

So, the width of the room is $\frac{108}{12}$ metres = $9$ metres.

Now, Let's assume that the height of the room is $h$ metres.

Now, According to the problem,

$2 \left(12 + 9\right) \times h = 252$ [The total surface area formula]

$\Rightarrow 2 \left(21\right) \times h = 252$

$\Rightarrow 42 h = 252$

$\Rightarrow h = \frac{252}{42} = 6$

So, The height of the room is $6$ metres.

Hence Explained.