Question: Can you guide me through solving this problem: Mara added 3 slices of cake to a plate that already had 2 slices on it. She was getting hungrier so she tripled the number of slices she currently has. She ate 2 slices and while she was distracted, her friend stole 5 slices off her plate. What number of cake slices remained on the plate?
Answer: 
Mara had 3+2=5 slices of cake.
She was hungry and tripled the amount to 5*3=15 slices.
She ate a couple, leaving 15-2=13 slices.
Her friend came and stole some which left Mara to 13-5=8 slices.