Japheth and Riordan each had the same volume of water. The water was used to pour into identical bottles. Japheth filled up 13 bottles and had 5.4 ℓ of water left. Riordan filled up 11 bottles and had 6.8 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 Japheth and Riordan had at first? Give your answer in litres.

(a)
Difference between the number of bottles
= 13 - 11
= 2

Difference between the volume of water left
= 6.8 - 5.4
= 1.4 ℓ

Volume of 2 bottles = 1.4 ℓ

Volume of 1 bottle
= 1.4 ÷ 2
= 0.7 ℓ

1 ℓ = 1000 mℓ
0.7 ℓ = 0.7 x 1000 = 700 mℓ

(b)
Volume of 11 bottles 
= 11 x 0.7
= 7.7 ℓ

Volume of water that Riordan had at first
= 7.7 + 6.8
= 14.5 ℓ

Total volume of water that Japheth and Riordan had at first
= 2 x 14.5
= 29 ℓ

Answer(s): (a) 700 mℓ (b) 29 ℓ