2Fe3O4 (s) + CO2 (g) 3Fe2O3 (s) + CO (g) ... balanced equation
Since the ∆H is positive 47.2 kJ for the reaction, this tells us it is endothermic and heat is absorbed.
This value of ∆H is for the reaction as written, i.e. it is heat absorbed 1 mole of CO2 reacts. We thus need to find out how many moles of CO2 we have in our current problem.
Moles CO2 = 35.15 g CO2 x 1 mol CO2/44.01 g = 0.7987 moles CO2
Now, we can convert this to kJ as follows:
0.7987 moles CO2 x 47.2 kJ/mole = 37.70 kJ absorbed