Suppose u = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10} is the universal set and g = {1, 2, 3, 4, 5, 6, 7}. what is g? can someone answer asap

Your posted question defines G, then asks what G is.
G is the set in the definition you gave.

G = {1, 2, 3, 4, 5, 6, 7}


Perhaps you want to know the complement of G. That is all the elements of U that are not in G.

G' = {8, 9, 10}