Can someone please help me with this?

Answer:
Step-by-step explanation:
As we can see it is a right angled triangle so
hypotenuse (h) = 14 . 7 km
perpendicular (p) = 11.9 km
base (b) = x
Now by using Pythagoras theorem
[tex]b^{2} = h^{2} - p ^{2}[/tex]
[tex]b^{2} = 14.7^{2} - 11.9^{2}[/tex]
[tex]b^{2} = 216.09 - 141.61[/tex]
[tex]b^{2} = 74.48\\b = \sqrt{74.48} \\b = 8.63 km[/tex]
Hope it was helpful.:)