Maths reasoning

1.A person walks 4 kilometers to the west, then turns to his right to travel 9km. He turns towards East and  walks 12 kilometers. He then turns to the south and walks a 3 kilometers. How far will he have to travel to reach the place where he started ? 

a.15

b.10

c.25

d.19

               

         Ans b.10.

we have to do like Pythagoras formula 

                                                              A²+B² =C²

where e ,g and a are right angle triangle
e to g =A
e to a =C
g to a =B

^{where A is 12-4 =8 km, B is 9-3 =6 km}

^{so 64+34=100}

^{that means c =10.}