Given that 1.12.91 is the first Sunday

Hence we can assume that 3.12.91 is the first Tuesday

If we add 7 days to 3.12.91, we will get second Tuesday

If we add 14 days to 3.12.91, we will get third Tuesday

If we add 21 days to 3.12.91, we will get fourth Tuesday

=> fourth Tuesday = [3.12.91 + 21 days ]= 24.12.91