What is the percent composition of k2S?

There is no such compound as k2S. But the % composition of K2S (potassium sulfide) is as follows:
2 K = 2 x 39 = 78
S = 32
Total mass = 78 + 32 = 110 g
%K = 78/110 (x100) = 70.9 % K
%S = 32/110 (x100) = 29.1 % S