Oscar and Vaidev each had the same volume of water. The water was used to pour into identical bottles. Oscar filled up 14 bottles and had 9.3 ℓ of water left. Vaidev filled up 12 bottles and had 9.9 ℓ of water left.

1. What was the capacity of each bottle? Give your answer in millilitres.
2. What was the total volume of water Oscar and Vaidev had at first? Give your answer in litres.

(a)
Difference between the number of bottles
= 14 - 12
= 2

Difference between the volume of water left
= 9.9 - 9.3
= 0.6 ℓ

Volume of 2 bottles = 0.6 ℓ

Volume of 1 bottle
= 0.6 ÷ 2
= 0.3 ℓ

1 ℓ = 1000 mℓ
0.3 ℓ = 0.3 x 1000 = 300 mℓ

(b)
Volume of 12 bottles 
= 12 x 0.3
= 3.6 ℓ

Volume of water that Vaidev had at first
= 3.6 + 9.9
= 13.5 ℓ

Total volume of water that Oscar and Vaidev had at first
= 2 x 13.5
= 27 ℓ

Answer(s): (a) 300 mℓ (b) 27 ℓ