A process can be described by the transfer functions:

$*$y$($s$)=2-$u$($s$)-3$s$+145$s$+$ d$($s$)1$

If a steady$-$state feedforward controller is used to regulate against the disturbance $\text{'}$d$\text{'}$ be manipulating $\text{'}$u$\text{'},$ calculate:

a$)$ the maximum error when d changes by a unit step. $($Up to $3$ decimal places$)$

b$)$ the time at which the maximum error will occur? $($secs$)$