A plant has a transfer function

$($a$)$ Calculate the value of the gain in dB for w$=4$rad$/$s

$($b$)$ If we choose a proportional controller with kp$=2,$ calculate the gain crossing frequency $($frequency for $0$dB gain$)$ in rad$/$s and the$$ phase margin in degrees.

$($c$)$ For how many more seconds can the current delay increase before making the system unstable.$$

Give all your answers to one decimal place.