19 + 16 = [(1 + 9) + (1 + 6)] x 3 = [10 + 7] x 3 = 17 x 3 = 51

13 + 13 = [(1 + 3) + (1 + 3)] x 3 = 8 x 3 = 24

Therefore we can find 10 + 10 as;

10 + 10 = [(1 + 0) + (1 + 0)] x 3 = 2 x 3 = 6.

Answer = 6