My baby is 7 month and half dr give him augmentin (amoxicillin and clavulanate) drops is okay or it should be 457 mg?

Dose by weight. This medicine is usually dosed by weight so a specific answer is not possible. Based on a typical weight for this age, a dose of 250mg twice a day would be reasonable.
Dose by weight. Dosing of Augmentin (amoxicillin and clavulanate) depends on age, weight, and what is being treated. For most 7 1/2 month old infants, appropriate dosing could range from 150 to 475 mg per day (usually divided into two or more smaller doses a day). Your baby's dose may be appropriate, but it depends on their weight and what is being treated. If given, watch for diarrhea and diaper rash.