<PRE><B>Question 689271</B>
North and west are at right angles

so pythagoras theorem will apply

the distance from starting point to the final point acts as the hypotenuse.

so apply pythagoras theorem
d^2= 15^2+9^2

d^2= 225+81

d^2= 306

d= sqrt(306)

d= 17.5 km

the distance from the starting point</PRE>