Upon strong heating, Cu2(CO3)(OH)2 or Cu3(CO3)2(OH)2 decomposes to leave CuO(s) in the heating crucible. Upon heating of 1.100 g of sample, 0.796 g remains. Calculate the %Cu in the sample.

I have added the atomic masses which comes to 221.1158g

The next step was to calculate the percentage of Cu in this sample, which I got 57.477763229%

I don't know how to proceed with this problem?