How is this scene related to the book 'English'?

Uncle Collin's savings are $45\%$ of the total investment of Shs 12,000,000.

$$\text{Savings} = 0.45 \times 12,000,000 = 5,400,000 \text{ Shs}$$

The loan amount is the total investment minus his savings.

$$\text{Loan Amount (Principal, P)} = 12,000,000 - 5,400,000 = 6,600,000 \text{ Shs}$$

The interest rate is $15\%$ per annum for 2 years.

$$\text{Interest (I)} = P \times R \times T$$ $$I = 6,600,000 \times 0.15 \times 2 = 1,980,000 \text{ Shs}$$ $$\text{Total Amount to Repay (A)} = P + I = 6,600,000 + 1,980,000 = 8,580,000 \text{ Shs}$$

The loan is for 2 years, which is $2 \times 12 = 24$ months.

$$\text{Monthly Payment} = \frac{\text{Total Amount to Repay}}{\text{Number of Months}} = \frac{8,580,000}{24} = \boxed{\text{357,500 Shs}}$$

The investment yields Shs 1,500,000 per month for 2 years.

$$\text{Total Income} = 1,500,000 \times 24 = 36,000,000 \text{ Shs}$$

The total cost includes the initial investment (which is the sum of savings and loan principal) and the interest paid on the loan.

$$\text{Total Cost} = \text{Initial Investment} + \text{Interest Paid}$$ $$\text{Total Cost} = 12,000,000 + 1,980,000 = 13,980,000 \text{ Shs}$$

$$\text{Profit} = \text{Total Income} - \text{Total Cost}$$ $$\text{Profit} = 36,000,000 - 13,980,000 = 22,020,000 \text{ Shs}$$

$$\text{Percentage Profit} = \frac{\text{Profit}}{\text{Total Cost}} \times 100\%$$ $$\text{Percentage Profit} = \frac{22,020,000}{13,980,000} \times 100\% \approx 157.5107\%$$

Rounding to two decimal places:

$$\text{Percentage Profit} = \boxed{\text{157.51\%}}$$