"1)"; v1 = Va a[t]/(a[t] + Ka); v2 = Vb b[t]/(b[t] + Kb); v3 = Vc c[t]/(c[t] + Kc); v4 = Vd d[t]/(d[t] + Kd); v5 = Ve e[t]/(e[t] + Ke); v6 = Vf f[t]/(f[t] + Kf); "2)"; Va = 1; Ka = 1; Vb = 1; Kb = 1; Vc = 1; Kc = 1; Vd = 1; Kd = 1; Ve = 1; Ke = 1; Vf = 1; Kf = 1; "3)"; NDSolve[{a'[t] == v6 - v1, b'[t] == v1 - v2, c'[t] == v2 - v3, d'[t] == v3 - v4, e'[t]==v4- v5, f'[t] == v5 - v6, a[0] == 1, b[0] == 0, c[0] == 0, d[0] == 0, e[0] == 0, f[0] == 0}, {a, b, c, d, e, f}, {t, 0, 15}]; "4)"; Plot[{Evaluate[a[t] /. %], Evaluate[b[t] /. %], Evaluate[c[t] /. %], Evaluate[d[t] /. %], Evaluate[e[t] /. %], Evaluate[f[t] /. %]}, {t, 0, 15}, PlotRange -> {0, 0.1}, PlotStyle -> {Gray, Thickness[0.01], Dashed, Thickness[0.01], Dashed, Thickness[0.01]}] "5)"; Plot[{Evaluate[a'[t] /. %], Evaluate[b'[t] /. %], Evaluate[c'[t] /. %], Evaluate[d'[t] /. %], Evaluate[e'[t] /. %], Evaluate[f'[t] /. %]}, {t, 0, 15}, PlotRange -> {0, 0.1}, PlotStyle -> {Gray, Thickness[0.01], Dashed, Thickness[0.01], Dashed, Thickness[0.01]}}]