Question 847608
a has 2^3 = 8 subsets: {}, {4}, {5}, {6}, {4,5}, {5,6}, {4,6}, {4,5,6}.


Your definition of set b is self-referential (b = {a,b,c} = {a, {a,b,c}, c} = {a, {a, {a,b,c}, c}, c} = ...) and it is unclear whether the previous set a is included. Assuming the elements of a second set B are {a,b,c}, B has eight subsets.