(a) A number divisible by 11 if difference sum of its digits at odd places and sum of its digits at even places is either 0 or a multiple of 11.

Sum of digits at odd places = 5 + 3 = 8

Sum of digits at even places = 3 + 5 = 8

8 - 8 = 0

Difference is 0

Hence, 5335 is divisible by 11.

(b) A number divisible by 11 if difference sum of its digits at odd places and sum of its digits at even places is either 0 or a multiple of 11.

Sum of digits at odd places = 4 + 8 + 2 + 9 = 23

Sum of digits at even places = 1 + 0 + 0 = 1

23 - 1 = 22

Difference is multiple of 11.

Hence, 9020814 is divisible by 11.