sum to infinitety??

(a)Find the sum ot infinity of the geometric series
1/2+(1/2)^2+(1/2)^3+....

(b)Let S be the sum to infinity of the series
1+3(1/2)+5(1/2)^2+7(1/2)^3+.....

(i)Show that S-1/2S is equal to the sum to infinity of the series
1+2(1/2)+2(1/2)^2+2(1/2)^3+.....

(ii)Hence find the value of S.

answers:(a)1 (b)(ii)6 pls.