kekuatan lensa kacamatanya adalah? toling pke cara dong,besok mau UAS hehe

1/f = 1/So + 1/Si
1/f = 1/30 + 1/-50
1/f = 5/150 - 3/150
1/f = 2/150
2f = 150
f = 75

P = 100/f
P = 100/75
P = 4/3 dioptri

*maap kalo salah