Total mixture = 42 litres in ratio $4:3$.
Total parts $= 4 + 3 = 7$.
Chemical A $= \frac{4}{7} \times 42 = 24\text{ litres}$.
Chemical B $= \frac{3}{7} \times 42 = 18\text{ litres}$.
When 12 litres of Chemical B is added:
New quantity of Chemical B $= 18 + 12 = 30\text{ litres}$.
New ratio $A : B = 24 : 30 = 4 : 5$.

Let total profit be $P$.
Management commission to Wajid $= 0.25P$.
Remaining profit to be shared $= 0.75P$.
Ratio of profit sharing (Investment $\times$ Time period):
Sajid: $70000 \times 12 = 840,000$
Wajid: $52500 \times 8 = 420,000$

Sajid's share of profit $= \frac{2}{3} \times 0.75P = 0.50P$.
Wajid's share of profit $= \frac{1}{3} \times 0.75P = 0.25P$.
Total received by Wajid $= \text{Commission} + \text{Profit share} = 0.25P + 0.25P = 0.50P$.
Given $0.50P = 60,000 \implies P = 120,000$.
Amount received by Sajid $= 0.50P = \text{Rs. } 60,000$.

Let son's present age be $S$, then father's present age $F = 7S$.
After 5 years:

Mixture concentration calculation:

• In the initial $150\text{ L}$ mixture:
  Volume of Water $= 20\% \times 150 = 30\text{ L}$.
  Volume of Wine $= 150 - 30 = 120\text{ L}$.
• Let $x$ liters of water be added. The volume of wine remains constant at $120\text{ L}$.
• In the new mixture, water is $25\%$, so wine is $75\%$ of the total volume:
  $75\% \times (150 + x) = 120$
  $\frac{3}{4} \times (150 + x) = 120$
  $150 + x = 120 \times \frac{4}{3} = 160$
  $x = 160 - 150 = 10\text{ litres}$.