30 people want 300 ml of soda. To find the total amount of soda we will need, we have to multiply the amount of soda (300 ml) by the number of people drinking soda (30).
300 * 30 = 9000 ml
We know that there are 1000 milliliters in a liter.
9000 ml / 1000 = 9 Liters
We know that we need 9 liters of soda for the 30 people.
However, the question asks how many 2 liter bottles you will need.
9/2 = 4.5
Therefore, you will need 4.5 two - Liter bottles of soda. (Some teachers may say that you can't buy half of a bottle of soda, so in that instance you would just buy 5 two-liter bottles.)