You are giving amoxicillin 25 ml po TID you have available 125mg/5ml how many mg are you giving at each dose

You will be giving 375mg per dose.
So, if ONE 5mL vial contains 125mg and you'll be giving 15 (which means you'll be giving 3 vitals of the 125mg dose) you'll just multiply 125mg x 3.
125 x 3 = 375.
For the T.I.D. your total dose for the day will equal 1125mg.