Number of containers for 2 litres of water = 1
So, number of containers for 1 litre of water = ½
So, number of containers for 30 litres of water
= ½ × 30
= 30/2
= 15
So, 15 of these containers would be needed to fill a 30-liter drum.
Answer:
1537pounds
Step-by-step explanation:
Given parameters:
Weight of baby at birth = 7.25 pounds
Unknown:
Weight at the end of 8months = ?
Solution:
From the second sentence;
Weight at the end of the eighth month = 212 x weight at birth.
Input the parameters and solve;
Weight at the end of eighth month = 212 x 7.25 = 1537pounds
and 
use the second expression to calculate the left-hand side of the first equation:

Add 10 to both sides if this equation to get

and divide both sides by 2

this proves that x = 17, give the two initial equations