According to the series the format is like
A+B+C
= B×C +1 +2+ n (n=0,1,2,3,4,.....n) ....(1)
And
For A+B+A
= A×A×B - 2+n (n=0,1,2,3,....n) .....(2)
so
according to the format (1)
4+7+2=7×2+4+2+0= 20
3+4+1=4×1+ 3+2+1 = 10
according to the format (2)
5+7+5=5×5×7-2+0 = 173
and now
as 4+8+3=? is following format (1)
then 4+8+3= 8×3+4+2+2=32
So the final answer is 4+8+3= 32.