Gibs free energy *gate question 2014

Triose phosphate isomerase converts dihydroxyacetone phosphate (DHAP)to glyceraldehyde  (G3P) in reversible reaction. At 298 K and pH 7 ,the equilibrium mixture contain 40mM DHAP and 4mM G3P .Assume that the reaction  started with 44 mM DHAP and no G3P .The standard free energy in Kj/mol for formation of G3P is__________
R=8.314j/mol.k


I'm getting 5.7 


But the ans key is showing 2.5 


Pz do help me with this sum