tolong dijawab yaa pake cara kalo bisa

[tex] \frac{1}{F} = \frac{1}{S₀} + \frac{1}{s₁} [/tex]
[tex] \frac{1}{15} = \frac{1}{20} + \frac{1}{s₁} [/tex]
[tex] \frac{1}{15} - \frac{1}{20} = \frac{1}{s₁} [/tex]
[tex] \frac{4}{60} - \frac{3}{20} = \frac{1}{s₁} [/tex]
[tex] \frac{1}{60 = \frac{1}{s₁} [/tex]
s₁ = 60

sifat = nyata , tegak, diperbesar