Numerical Question 7 and 8

Please refer to the image for the question

7. The open lop transfer function of a negative feedback control system is given, then what is the value of Kc for unstable condition of the system. G(s)=X(s)Y(s)=(s+3)(s+6)Kc(e4s) (Write answer up to one decimal digit) Ans. 20.5 8. The open loop transfer function for a process is 4(3s+1)41 where the time is in minutes. The crossover frequency and ultimate gain respectively are: Ans. 0.333rad/ time and 16