What Is The Correct Dosage Of Augmentin Duo For My 6-year-old If It Is Prescribed Three Times A Day?

Good morning sir.my brother age is 6.5 years .He had cough since yesterday . Dr . Prescribed medicine augmentin dds 457mg/5ml and dr said to give 5ml thrice a day .but this medicine is not available shopkeeper give me augmentin duo 3.3g/30ml how many ml and dosage should I give of augmentin duo