From the given picture, we have a right triangle and we can apply Pythagorean theorem to find x, that is,
[tex]x^2=12^2+7^2[/tex]
which gives
[tex]\begin{gathered} x^2=144+49 \\ x^2=193 \end{gathered}[/tex]
Then, by applying square root in both side, we get
[tex]x=\sqrt[]{193}\text{ km}[/tex]
Then, the answer is option B.
