I am confused about how to do this kind of question. How do I approach this?

This question is based on formation enthalpies.
First right the balanced equation
C3H8(g)+5O2(g) →  3CO2(g)+4H2O(g)
Use the formation-enthalpy  equation

here apply the coefficients of the balanced equation
Plug in the values from the given table and you will get ΔH⁰comb in kJ / mol
Answer should be in kJ/g so convert 1mol into grams.
All questions based on formation enthalpies are done by using the equation given above.