Consult Table 9.1 while working this problem - it is very important that you know these shapes and why certain numbers of electron domains take on certain geometries!
Three electron domains will assume a planar arrangement with 120o angles between them to minimize repulsion. This is the trigonal planar shape.
Four electron domains will orient themselves at 109.5o angles. This shape is tetrahedral.
Five electron domains will orient themselves with three pairs at 120o angles in the plane around the central atom (the equatorial positions) and two pairs 180o apart (the axial positions.) This is the trigonal bipyramidal shape.
Six electron pairs will orient themselves at 90o to one another - this is the octahedral electron-domain geometry.