Figure below shows the block diagram of a dc-motor control system (note the dc-motor is represented by G(s)= K(s+3)/s(s+1)(s+2).The signal N(s) denotes the frictional torque at the

Question

Figure below shows the block diagram of a dc-motor control system (note the dc-motor is represented by G(s)= K(s+3)/s(s+1)(s+2).The signal N(s) denotes the frictional torque at the 
motor shaft.

a) Find the transfer function H(s) so that the output Y(s) is not affected by the disturbance torque N(s).

b) With H(s) as determined in part a), find the value of K so that the steady-state value of e(t) is equal to 0.1 when the input is a unit-ramp function, r(t)=tu(t) and N(s) = 0 . Apply the final-value theorem.

The figure(block diagram) is in this PDF FILE "ECEN 4413 Automatic Control System Spring 2005 Midterm Exam 1". I cannot post url here so you can just search in google,Sorry..but pls help me..:(

It's problem number 4 there..PLS I really need your help..THANK YOU!!