Could you pleas guide for gams code to use for question

Dynamic Model of the Reactor Consider the following Ordinary Differential Equations model of the ammonia reactor: dTf dx u S = (Tg - Tf) W Cpf dTg dx = W Cpg u S - (Tg - Tf) + (-AH)S2 W Cpg (1) (2) dNN2 dx == where = f (k 1.5 PN2 PH2 PNH3 - k2 PNH3 1.5 PH2 -20800 k = 1.78954 x 10 exp RTg -47400 k = 2.5714 x 1016 exp PN2 PH = 286 NN2 2.598NN 2.0 + 2 NN 3 PN RTg (3)