Answer
See the answer below.
Work Step by Step
a) It's a cubic shape with atoms in every face: face-centered cubic.
b) Each anion is surrounded by 4 cations, so they are in tetrahedral holes
c) Calcium: $8\times 1/8=1$ ions in the vertexes, $6\times 1/2=3$ in the faces, 4 in total
Fluorine: 8 inside the cell
Formula: $CaF_2$
