Jawabanmu

2014-06-02T14:25:05+07:00
S' =  \frac{S . f}{S - f}
S' =  \frac{20 . 4}{20 - 4}
S' =  \frac{80}{16}
S' = 5 cm

M =  \frac{S'}{S}
M =  \frac{5}{20}
M =  \frac{1}{4} X
1 4 1