There was 21.6 litres of water altogether in container A and container B. The water level in container A was the same as container B. The base area of container A was 700 cm^2 and the base of container B has dimensions as shown.

1. Convert the total volume of water from litres to cubic centimetres

$21.6 \text{ litres} = 21.6 \times 1000 = 21600 \text{ cm}^3$

2. Calculate the base area of container B

$\text{Base area of B} = 40 \times 50 = 2000 \text{ cm}^2$

3. Find the total base area of both containers

$\text{Total base area} = 700 + 2000 = 2700 \text{ cm}^2$

4. Calculate the common height of water in both containers

$h = \frac{21600}{2700} = 8 \text{ cm}$

1. Calculate the volume of water currently in container A.

From part (a), the common height $h = 8\text{ cm}$.
Volume in A $= 700 \times 8 = 5600\text{ cm}^3$.

2. Calculate the volume of water currently in container B.

Volume in B $= 2000 \times 8 = 16000\text{ cm}^3$.

3. Determine the target volume for each container to have the same amount.

Total volume $= 21600\text{ cm}^3$.
Target volume per container $= 21600 \div 2 = 10800\text{ cm}^3$.

4. Identify which container to pour from and calculate the amount.

Since $16000 > 10800$, water must be poured out from container B.
Amount to pour $= 16000 - 10800 = 5200\text{ cm}^3$.