Answer
$\text{We label the displacement vectors $\vec{A}, \vec{B},$ and $\vec{C}$ (and denote the result of their }$ $\text{ vector sum as ). We choose east as the $\hat{i}$ direction (+x direction) and north as}$ $\text{the $\hat{j}$ direction}$ $(+y \text { direction }).$
$\text{We note that the angle between $\vec{C}$ and the $x$ axis is $60^{\circ} .$ Thus, }$
$\text{see the image below:} \downarrow$
$\text{The total displacement of the car from its initial position is represented by}$
$$
\vec{r}=\vec{A}+\vec{B}+\vec{C}=(62.5 \mathrm{km}) \hat{\mathrm{i}}+(51.7 \mathrm{km}) \hat{\mathrm{j}}
$$
$\text{which means that its magnitude is}$
$$
|\vec{r}|=\sqrt{(62.5 \mathrm{km})^{2}+(51.7 \mathrm{km})^{2}}=81 \mathrm{km} .
$$
Work Step by Step
$\text{We label the displacement vectors $\vec{A}, \vec{B},$ and $\vec{C}$ (and denote the result of their }$ $\text{ vector sum as ). We choose east as the $\hat{i}$ direction (+x direction) and north as}$ $\text{the $\hat{j}$ direction}$ $(+y \text { direction }).$
$\text{We note that the angle between $\vec{C}$ and the $x$ axis is $60^{\circ} .$ Thus, }$
$\text{see the image below:} \downarrow$
$\text{The total displacement of the car from its initial position is represented by}$
$$
\vec{r}=\vec{A}+\vec{B}+\vec{C}=(62.5 \mathrm{km}) \hat{\mathrm{i}}+(51.7 \mathrm{km}) \hat{\mathrm{j}}
$$
$\text{which means that its magnitude is}$
$$
|\vec{r}|=\sqrt{(62.5 \mathrm{km})^{2}+(51.7 \mathrm{km})^{2}}=81 \mathrm{km} .
$$
