a) $v\left( 4 \right) = 0.75 \times 4$

$v\left( {54} \right) = v\left( 4 \right)$ and $v\left( {60} \right) = v\left( {54} \right) - 0.5\left( {60 - 54} \right)$

Velocity is $3m{s^{ - 1}}$ when $t = 4$ and 0 when $t = 60$

${2^{nd}}$ segment has zero slope; end points of segments are seen to be correct

$\left\{ {\left( {0,0} \right),{\text{ }}\left( {4,3} \right),{\text{ }}\left( {54,3} \right),{\text{ }}\left( {60,0} \right)} \right\}$

b) [$XY = {\raise0.5ex\hbox{$\scriptstyle 1$}
\kern-0.1em/\kern-0.15em
\lower0.25ex\hbox{$\scriptstyle 2$}}\left( {60 + 50} \right) \times 3$

or

$XY = {\raise0.5ex\hbox{$\scriptstyle 1$}
\kern-0.1em/\kern-0.15em
\lower0.25ex\hbox{$\scriptstyle 2$}} \times 0.75 \times {4^2} + 3 \times 50 - {\raise0.5ex\hbox{$\scriptstyle 1$}
\kern-0.1em/\kern-0.15em
\lower0.25ex\hbox{$\scriptstyle 2$}}x0.5 \times {6^2}$]

Distance is $165m$