Laxmi and Prasanna set on a journey. Laxmi moves northwards at a speed of 40kmph and Prasanna moves southward at a speed of 38 kmph. How far will be Prasanna from Laxmi after 60 minutes ? Choices:
A) 11 B) 50 C) 78 D) 27 E) 18

Rationale: "explanation : we know 60 min = 1 hr total northward laxmi ' s distance = 40 kmph x 1 hr = 40 km total southward prasanna ' s distance = 38 kmph x 1 hr = 38 km total distance between prasanna and laxmi is = 40 + 38 = 78 km . answer : c"
Answer: C