Calculate the least share for problem 19c, and the HCF, LCM, and their product for problem 20a.

Multiply the value per part by 3.

$$\text{Least share} = 3 \times \text{₦}20,000 = \text{₦}60,000$$

The least share is $\boxed{\text{₦}60,000}$.

:

This is the product of the lowest powers of common prime factors. The only common prime factor is 3, and its lowest power is $3^1$.

$$\text{HCF}(9, 12, 18) = 3$$

This is the product of the highest powers of all prime factors present. - Highest power of 2 is $2^2$. - Highest power of 3 is $3^2$.

$$\text{LCM}(9, 12, 18) = 2^2 \times 3^2 = 4 \times 9 = 36$$

$$\text{Product} = \text{LCM} \times \text{HCF} = 36 \times 3 = 108$$

The product of the LCM and HCF is $\boxed{108}$.

:

$$\text{SI} = \frac{30000 \times 17.5}{100}$$ $$\text{SI} = \frac{525000}{100}$$

$$\text{SI} = \text{₦}5250.00$$

The simple interest is $\boxed{\text{₦}5250.00}$.

:

$$\text{Loss} = \text{Cost Price} - \text{Selling Price}$$ $$\text{Loss} = \text{₦}45,000 - \text{₦}30,000 = \text{₦}15,000$$

$$\text{Loss Percent} = \frac{\text{₦}15,000}{\text{₦}45,000} \times 100\%$$ $$\text{Loss Percent} = \frac{1}{3} \times 100\%$$ $$\text{Loss Percent} = 33.33\% \text{ (to 2 decimal places)}$$

The loss percent is $\boxed{33.33\%}$.