60.0 mL of 0.60 M HCOOH and 40.0 mL of 0.80 M CH3NH2, both initially at 22.0 °C, are mixed in a well — Thermochemistry Chemistry Question

60.0 mL of 0.60 M HCOOH and 40.0 mL of 0.80 M CH₃NH₂, both initially at 22.0 °C, are mixed in a well-insulated container. The final temperature is 27.9 °C. What is ∆H°rxn for the reaction of formic acid and methylamine? Assume that the densities and specific heat capacities of all solutions are the same as pure water.
HCOOH(aq) + CH₃NH₂(aq) → HCOO–(aq) + CH₃NH³⁺(aq)
∆H°rxn = ???