Tolong dijawab ya beserta caranya…

1/f = 1/so + 1/si
1/f = 1/15 + 1/30
1/f = 1/30 + 1/30

1/f = 3/30
f. = 30 / 3
f. = 10cm

jika so mendekati cermin cekung sebesar 3cm maka

1/f = 1/so + 1/si
1/si = 1/f – 1/so
1/si = 1/10 – 1/12
1/si = 6/60 – 6/50

1/si = 1/60
si. = 60 yang D