FIND THE SUM OF INFINITY OF THE G.P 3+3/10+3/10

3 6/10

You appear to have a typo in your sequence

The way it sits, it is not a geometric sequence
perhaps you meant :
3, 3/10, 3/100 .... ??
I will assume that's what it is, adjust my solution if otherwise.

a = 3,
r = 1/10

sum(all terms) = a/(1-r)
= 3/(1-1/10 )
= 3 / (9/10) = 3(10/9) = 30/9 = 10/3