I believe it would be 9,261 inches of water to fill the new cube.
To find the maximum capacity of a cube you have to multiply s*s*s (each s stands for one of its sides)
The side length happens to be 7. 7 times 7 times 7 is 343. If we triple that length now it’ll be 21. Multiply 21 by 21 by 21 it’ll give you 9,261 inches
