The whole angles of the square is \(360^0\)

The pizza is cut into 12 congruent slices => Each slice has the angle of \(\dfrac{360}{12}=30^0\)

So the sum of the central angles of the slices that were not eaten after ate 2 slices is :

\(360-30\cdot2=360-60=300^0\)

Answer : \(300^0\)