If 18 dolls cost Rs.630, how many dolls can be bought for Rs.455?
More the dolls, more will be the cost. So it is a direct proportion.
Let no. of dolls be x, 
⇒ 630 × x = 18 × 455
⇒ x = 
= 13
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If 18 dolls cost Rs.630, how many dolls can be bought for Rs.455?
More the dolls, more will be the cost. So it is a direct proportion.
Let no. of dolls be x,
⇒ 630 × x = 18 × 455
⇒ x = = 13