During glycolysis, triose phosphate isomerase catalyzes the…

During glycolysis, triose phosphate isomerase catalyzes the net conversion of dihydroxyacetone phosphate to glyceraldehyde-3-phosphate. The standard free energy change (∆G°) for this reaction is positive (+7.9 kJ/mol). During glycolysis, why is the net reaction the formation of glyceraldehyde-3-phosphate?