Question

If 18 dolls cost Rs 630, how many dolls can be bought for Rs 455?

Answer 1

Let the required number of dolls be x. Then, we have:

No of dolls	18	x
Cost of dolls (in rupees)	630	455

Clearly, the less the amount of money, the less will be the number of dolls bought.
So, this is a case of direct proportion.
$$\begin{gathered} \mathrm{Now},\frac{18}{630}=\frac{x}{455} \\ \Rightarrow \frac{1}{35}=\frac{x}{455} \\ \Rightarrow x=\frac{455}{35} \\ \Rightarrow x=13 \end{gathered}$$

Therefore, 13 dolls can be bought for Rs 455.