Jawabanmu

2014-06-02T17:32:08+07:00
1/f = 1/Si + 1/So
1/15 = 1/Si + 1/20
1/Si = 1/15- 1/20
1/SI. = 1/60
Si = 60cm

Si . ho = So . hi
60. 5. = 20 . hi
300. = 20 . hi
hi. = 15 cm. (ukuran bayangan)