Jawabanmu

2014-04-23T22:14:04+07:00
1/f = 1/so + 1/si
1/15 = 1/so + 1/30
1/15 - 1/30 = 1/so
2/30 - 1/30 = 1/so
1/30 = 1/so
so = 30 cm 


f    = fokus
so = letak benda
si  = letak bayangan
1 5 1