From the information given, the two walk in opposite direction and later turn to walk towards left hand side. Therefore, it can be said that one walked towards North and the other towards South. Then, depending on the side of observation, one would turn to the East and the other to the West.
The result is two triangles whose hypotenuses do add up to indicate the distance between Mustafa and Deni. The vertical legs of the triangles is 4 m and horizontal legs are 3 m.
Now, using the hypotenuse formula;
C = Sqrt (a^2+b^2); where a = 3 m, and b = 4 m
Substituting;
Distance between the two = 2C = 2*Sqrt (3^2+4^2) = 2*5 = 10 m
