For the system in Figure $3$:

a$)$ Find the transfer function of the system with no disturbance $)=(0.$

b$)$ If the input is a step function, $r(t)=5u(t),$ find the steady$-$state output, $y_{ss},$ assuming there is no disturbance.

c$)$ Now assume a ramp disturbance is applied, $d(t)=2t,$ and that $r(t)=0.$ Find the steady$-$state output generated by this disturbance.