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 309 kJ ---------------------- x -------------------- = 402 kJ 2 moles A
