Total water volume = sum of volumes of both cuboids.
• First cuboid: 24 × 15 × 6 = 2160 cm³
• Second cuboid: 18 × 12 × 5 = 1080 cm³
• Total water = 2160 + 1080 = 3240 cm³
Tank volume = 24 × w × 9 = 216w.
216w = 3240
w = 3240 ÷ 216 = 15 cm.
Final Answer: 15 cm