In a journey of 24 miles, two thirds of the distance was travelled with a speed of 40 mph and the remaining with 60 mph. How much time did the journey take?

A. 14.4 minutes
B. 20 minutes
C. 28.8 minutes
D. 32 minutes
(2/3)*24=16 miles Time taken to cover the first 16 miles
= (16/40) hours
= 24 minutes Time taken to cover the next 8 miles
= (8/60) hours
= 8 minutes Time taken for the entire journey
= 32 minutes