Step 1: Let the original catalog price be $P$ Tk.

The man got a 20% discount, so he paid 80% of the original price:

$$\text{Selling price} = 80\% \text{ of } P$$ $$360 = \frac{80}{100} \cdot P$$ $$360 = 0.8 P$$

Step 2: Solve for $P$

$$P = \frac{360}{0.8}$$ $$P = 450$$

Answer: Original catalog price = Tk. 450

Step-by-step solution:

1. Original price (Cost price, CP): Tk. 25

2. Selling price (SP): Tk. 75

3. Percent increase formula:

$$\text{Percent Increase} = \frac{\text{SP} - \text{CP}}{\text{CP}} \times 100$$

4. Substitute the values:

$$\text{Percent Increase} = \frac{75 - 25}{25} \times 100$$ $$\text{Percent Increase} = \frac{50}{25} \times 100$$ $$\text{Percent Increase} = 2 \times 100$$ $$\text{Percent Increase} = 200\%$$

Answer: 200%

Let $x\%$ of $a$ be equal to $3a$. Then:

$$\frac{x}{100} \times a = 3a$$

Divide both sides by $a$ (assuming $a \neq 0$):

$$\frac{x}{100} = 3$$

Multiply both sides by 100:

$$x = 300$$

Answer: $300\%$ of $a$ is equal to $3a$.