To add the given fractions, we first need to convert them into a common denominator.

8ц 13/20 + 11ц 19/30
= (8 20 + 13) / 20 + (11 30 + 19) / 30
= (160 + 13) / 20 + (330 + 19) / 30
= 173 / 20 + 349 / 30

To find a common denominator for the fractions, we need to find the least common multiple of 20 and 30, which is 60.

So, we can rewrite the fractions with the common denominator:
= (173 3) / (20 3) + (349 2) / (30 2)
= 519 / 60 + 698 / 60
= (519 + 698) / 60
= 1217 / 60

Now, we simplify the fraction if needed:
1217 ÷ 60 = 20ц 17/60

Therefore, 8ц 13/20 + 11ц 19/30 = 20ц 17/60.

Now, let's find the sum of the second pair of fractions:

9ц 7/20 + 12ц 11/30
= (9 20 + 7) / 20 + (12 30 + 11) / 30
= (180 + 7) / 20 + (360 + 11) / 30
= 187 / 20 + 371 / 30

To find a common denominator for the fractions, we need to find the least common multiple of 20 and 30, which is 60.

So, we can rewrite the fractions with the common denominator:
= (187 3) / (20 3) + (371 2) / (30 2)
= 561 / 60 + 742 / 60
= (561 + 742) / 60
= 1303 / 60

Now, we simplify the fraction if needed:
1303 ÷ 60 = 21ц 43/60

Therefore, 9ц 7/20 + 12ц 11/30 = 21ц 43/60.

Finally, adding both sums together:
(20ц 17/60) + (21ц 43/60) = 41ц 60/60 = 41ц 1/1 = 42ц 0/1 = 42ц.

Therefore, the final sum is 42ц.