Jawabanmu

2014-05-10T16:50:55+07:00
1/s + 1/s' = 1/f
1/12 + 1/s' = 1/18
1/s' = 1/18 - 1/12
1/s' = 2/36 - 3/36
1/s' = -1/36
s' = -36 cm (36 cm di belakang cermin)

Jarak antara benda dan bayangan = 36 - 12 = 24 cm