help me with the solution

Consider the block diagram shoyn in Fig Q3 with the folloying transfer functions: Gv=s+15;Gp1=(4s+1)(2s+1)4;Gd1=3s+11Gp2=Gd2=1;Gm1=0.05;Gm2=0.2 where the time constants have units in minutes and the gains have constant units. Determine the stability limits for a conventional proportional controller as well as for a cascade control system consisting of two proportional controllers. Assume Kc2=5 for the secondary controller. [25] Fig Q3 Block diagram for a cascade control system