Step 1: Old ratio
Rana : Sana : Kamana = 4:3:2 = total 9 parts.
\[
\text{Sana old share} = \frac{3}{9} = \frac{1}{3}, \text{Kamana old share} = \frac{2}{9}
\]
Step 2: New ratio after Rana retires
Sana : Kamana = 5:3 = total 8 parts.
\[
\text{Sana new share} = \frac{5}{8}, \text{Kamana new share} = \frac{3}{8}
\]
Step 3: Calculate Gain
\[
\text{Sana's gain} = \frac{5}{8} - \frac{1}{3} = \frac{15 - 8}{24} = \frac{7}{24}
\]
\[
\text{Kamana's gain} = \frac{3}{8} - \frac{2}{9} = \frac{27 - 16}{72} = \frac{11}{72}
\]
Step 4: Express gains in ratio
Take LCM = 72.
\[
\text{Sana's gain} = \frac{7}{24} = \frac{21}{72}, \text{Kamana's gain} = \frac{11}{72}
\]
So ratio = 21 : 11.
Final Answer: \[ \boxed{\text{Gaining Ratio = 21:11}} \]