Answer: 9.2
Step-by-step explanation: well if you have 10 kids and you already have both averages (8 and 12) all you have to do is multiply the averages by the amount of students so 7 x 8 = 56 and 3 x 12 = 36 then you add 56 + 36 which = 92 then you divide by 10 which gives you 9.2