Answer the question of tourism

Formula:

$$\text{Percentage increase} = \frac{\text{revenue}_{2021} - \text{revenue}_{2020}}{\text{revenue}_{2020}} \times 100\%$$

Substitute revenue$_{2020} = 1200$ million dollars, revenue$_{2021} = 1500$ million dollars:

$$\frac{1500 - 1200}{1200} \times 100\% = \frac{300}{1200} \times 100\% = 0.25 \times 100\% = 25\%$$

25%

Formula:

$$\text{Total revenue} = \text{revenue}_{2020} + \text{revenue}_{2021} + \text{revenue}_{2022}$$

Substitute revenue$_{2020} = 1200$ million dollars, revenue$_{2021} = 1500$ million dollars, revenue$_{2022} = 1800$ million dollars:
$1200 + 1500 + 1800 = 4500$ million dollars

4500 million dollars

Formula:

$$\text{Average revenue} = \frac{\text{total revenue}}{3}$$

Substitute total revenue = 4500 million dollars:
$\frac{4500}{3} = 1500$ million dollars

1500 million dollars