Answer:
2.5 L
Explanation:
We use a rule of three to solve this problem, the information we have is represented as follows:
Liters People
1 ⇒ 20
x ⇒ 50
x represents the unknown quantity, the liters that correspond to 50 people.
The way x is found is as follows: We multiply the cross quantities and divide by the remaining quantity.

Thus, for 50 people is provided 2.5 liters of water