could you possibly help me out? I am stuck on two questions

the general term of an infinite sereis is tn= ( pie square) (3/11)^ n+1. how many terms must be added to reach a sum that is greater than 0.32?

t1 = (pie square) (3/11)2 = 0.233672181

r = (3/11)

Sm = a * (1-rm)/(1-r)

0.32 * 8/11 = 0.233672181 * (1-rm)

I know I have to use logarithm but I get confused!

my second question!

convert 0.12 ( repeating decimal ) to a fraction using algebraic method!

I know that I would use the fomula :

s= a/ 1-r or am I totally wrong? can you guiys explain to me how I woudl do this question?