Jawabanmu

2014-02-23T11:41:30+07:00
F=10cm
So=30 cm
S'=?
1/f=1/So+1/S'
1/s'=1/f-1/So
     =1/10-1/30
    =3/30-1/30
    =2/30
    =1/15
S'=15 cm
2014-02-23T11:44:34+07:00
S = s x f : s - f 
   = 30 x 10 : 30 - 10 = 300 : 20 = 15