We need to solve the speed formula for d. To do so, let's start by moving the number of the left hand side:
[tex] \frac{S}{356} = \sqrt{d} [/tex]
Square both sides to get rid of the square root:
[tex] \frac{S^2}{126736} = d [/tex]
Now plug the known value of the speed to find the distance:
[tex] d = \frac{140^2}{126736} = \frac{19600}{126736} \approx 0.15465 [/tex]
So the closest answer is the last one: d=0.155km
