???? yu hav sum numbers with averaej=8,
then add 28 & nu averaej=9 ???
averaej=sum/(num numbers)=sum/n
(sum+28)/(n+1)=9 & sum/n=8
equashun 1: sum+28=9n+9
eqiasjim 2 sum=8n
subtraks...28=n+9, so n=28-9, so n=19
sum=8*19=152, nu sum=152+28=180 & 180/20=9