{ diff(x1, t) = (-1)*k11*(k8*2187/5000 + k9*1957/5000 + k10*4047/10000)*k2*(1 - (k8*49/625 + k9*9/200 + k10*233/5000))^t*x1*x2/(x2 + x3 + x1)/k11,
  diff(x2, t) = (1*k11*(k8*2187/5000 + k9*1957/5000 + k10*4047/10000)*k2*(1 - (k8*49/625 + k9*9/200 + k10*233/5000))^t*x1*x2/(x2 + x3 + x1) + (-1)*k11*(k8*1/40 + k9*21/500 + k10*1/20)*x2)/k11,
  diff(x3, t) = 1*k11*(k8*1/40 + k9*21/500 + k10*1/20)*x2/k11 }