Diego baked 12 cakes for his sister's birthday. Donald also baked 4 cakes, but ate 1 while waiting for the party to start. How many cakes are left?
Please answer the following question by reasoning step-by-step.
15
The total number of cakes baked is 12 + 4 = 16 cakes.

But since Diego ate 1 cake, there are 16 - 1 = 15 cakes left.

.

Thus, the answer is 15