Find the allowable complex plane regions?

For the transfer function (a+B)/[s(s+1)+a+b] it is required that the max overshoot (Mp) and settling time (ts) not exceed 9.5% and 2.558 seconds. Find the allowable complex plane regions for the poles of the overall system transfer. Note that the settling time should be based on an acceptable oscillation amplitude (Ms) of 1% (i.e. Ms=0.01)