Answer:
402 kJ
Explanation:
Because the energy of the reaction is positive, the reaction is endothermic. This means energy is a reactant.
You can determine how much energy/heat is absorbed using the balanced chemical equation. You can convert the moles A using the ratio composed of the coefficient in front of A and the energy required for each reaction.
2A + B + 309 kJ ⇌ 2C + 2D
2.60 moles A Â Â Â Â Â Â 309 kJ
----------------------  x  --------------------  = 402 kJ
                 2 moles A