Two friends A and B leave City P and City Q simultaneously and travel towards Q and P at constant sp...........

Explanation:

Let us assume Car A travels at a speed of a and Car B travels at a speed of b.
Further, let us assume that they meet after t minutes.
Distance traveled by car A before meeting car B = a * t. Likewise distance traveled by car B before meeting car A = b * t.
Distance traveled by car A after meeting car B = a * 54. Distance traveled by car B after meeting car A = 24 * b.
Distance traveled by car A after crossing car B = distance traveled by car B before crossing car A (and vice versa).
=> at = 54b ---------- (1)
and bt = 24a -------- (2)
Multiplying equations 1 and 2
we have ab * t² = 54 * 24 * ab
=> t² = 54 * 24
=> t = 36
So, both cars would have traveled 36 minutes prior to crossing each other.
Or, B would have taken 36 + 24 = 60 minutes to travel the whole distance.