Which of the following equations can be used to determine the change in enthalpy of a system?

ΔHreaction=ΔHproducts×ΔHreactants

ΔHreaction=ΔHproducts÷ΔHreactants

ΔHreaction=ΔHproducts+ΔHreactants

ΔHreaction=ΔHproducts−ΔHreactants