Base address = 10. It means address of A[1][1][1] = 10.
Dimension of 3-D array = A[90][30][40].
Note- Since elements in 3-D array are stored in column major order, So we can say that we have total 40 layers of (30*90) 2-D array.
Assuming given array elements are integer and it takes 4 bytes of memory address.
Location of A[20][20][30] = 10 + (19 * (90*30) + 19* 90 + 20 -1 )*4
= 10 + 53029*4
= 212126