What is the percent composition of NiO, if a sample of NiO with a mass of 41.9 g contains 33.1 g Ni and s g O?

Well it has 79.0% metal content.........
%Ni=(33.1*g)/(41.9*g)xx100%=79.0%
%O=(41.9*g-33.1*g)/(41.9*g)xx100%=21.0%