How do you solve Hess's law problems?

write out the balanced equation that you need then write out formation equations (2-4) that will give you those reactants and products. manipulate the equations by reversing them or multiplying or dividing by whatever number. until you have what you need for the original equation. whatever you do to the equation, do it to the enthalpy for that equation. everything should add or cancel until you have the equation needed and you can add the enthalpies to get the enthalpy for that equation