tolong dong..... soal cermin( fisika )

So = 30
Si = 2 × 30 = 60
1/f = 1/so + 1/Si
1/f = 1/30 + 1/60
1/f = 2+1/60
1/f = 20
F = 20
So = 30-14 = 16
Si = 1/20-1/16
Si = 4-5 / 80
Si = -1/ 80
Si = -80
(benda di ruang satu, jadi bayangan sifatnya Maya)
perbesaran = Si : So
perbesaran = -80 : 16
perbesaran = -5 atau 5