The total number of cakes baked is 12 + 4 = <<12+4=16>>16 cakes.

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

# Answer

15
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
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 reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
15
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?
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