the numbers in serial distinctly gives the trend of relation amongst , first 3 numbers 4 , 6 , 8 are in increasing order of 2 , and in rest 3 numbers 12,18 and 24 , they are in increasing order of 6 .
so , first blank no will fall after 18 with increasing order of 2 which is 10 , similarly second blank number will be in increasing order of 6 to 24 which is 30.