Answer
Combustion reactions are exothermic since it releases heat to the surroundings.
Explanations:
A reaction can either be exothermic or endothermic depending on the enthalpy change of the reaction. If the enthalpy change is positive, the reaction is known to be endothermic, it is negative, it is an endothermic reaction.
For a combustion reaction, a substance burns when it combines with oxygen, thereby releasing energy in the form of heat. Hence we can tell that combustion reaction is an exothermic reaction due to the release of energy to the surroundings after the reaction