Chapter 10 - Review Exercises - Page 708: 1

{0}, {Dave},{Joanne},{Erica}, {Joanne, Erica},{Joanne, Dave},{Dave, Erica}, {Joanne, Erica, Dave}

The number of subsets we have is $2^n$ where $n$ is the number of elements. We have the null set, {0}, We have the single groupings, {Dave},{Joanne},{Erica} The doubles, {Joanne, Erica},{Joanne, Dave},{Dave, Erica} And the triple {Joanne, Erica, Dave}