[tex]\frac{3s}{\frac{4}{18}} = 3s : \frac{4}{18} = 3s . \frac{18}{4} = \frac{54s}{4}[/tex]
Tương tự, [tex]\frac{1s}{\frac{4}{36}}[/tex] = [tex]\frac{36s}{4} =[/tex] 9s
Kết quả
[tex]\frac{s}{\frac{3s}{\frac{4}{18}} + \frac{1s}{\frac{4}{36}}}[/tex] = [tex]\frac{s}{13,5s + 9s} = \frac{1}{22,5}[/tex]