Let the number 'a' be the common divisor for the given numbers
so the numbers are 2a , 3a and 4a.
it is given that the sum of the cubes of 2a , 3a and 4a is 33957
so 99 times the cube of 'a' is 33957
⇒cube of a is 343
a = 7
so the numbers are 14 , 21 , 28.