<PRE><B>Question 892728</B>
Jack droved at 80 km/s for the first 5/9 of his journey. he then completed the remaining 24 km of his journey in 12 minutes.
how long did he take to complete the whole journey?
what was his speed for the second part of his journey?
I will assume you meant 80 km/hr instead of 80 km/sec for the first part of the journey
***
let x=total distance of the journey
4/9=24/x
4x=9*24
x=54 km
(5/9)x=30 km
..
for the first 5/9 of his journey 
travel time=distance/speed
30 km/80 km/hr=3/8 hr=22.5 min
..
for the second part of his journey
speed=distance/travel time
24 km/(12/60) hr=120 km/hr
how long did he take to complete the whole journey=22.5+12=34.5 min
what was his speed for the second part of his journey=120 km/hr</PRE>