I'm balancing chemical equations, and I came across the following:<br>
$$\ce{O2 + C4H9NH2 ->  CO2 + H2O + N2}\tag{unbalanced}$$

My initial reaction was that it is a combustion reaction. According to my workbook, the definition is "an organic compound reacts with oxygen to form carbon dioxide and water." This equation seems to fit the bill. However, the solution states that in fact this is a decomposition reaction. In a YouTube video I saw, it said that decomposition reactions are a single reactant to multiple products. Where is the misunderstanding? Is it possible the workbook is wrong?