Answer:
15 slices
Step-by-step explanation:
The total number of slices is equal to 60 (6x10=60) and if each friend eats 3 slices, they will all collectively eat 45 slices (15x3). If they eat 45 out 60 slices they will have 15 slices left over (60-45=15).
The solution is in the attachment
