Question 2154
 If the give two speeds are v1(< v2) with distance D,then
 the time for the 2nd vehicle to overtake the 1st vehicle is
  T = D/(v2 - v1).

 Now,D = 40* 24/60 = 40* 2/5 = 16 miles,

 Hence, T = 16/(50-40) = 1.6 hours

 We learned this question in primary school,so you have to
 work hard.