<PRE><B>Question 1154666</B>

A person covers 2/3 of his journey at his usual speed and the remaining distance at 3/4 of the usual speed and takes 30min more than the usual time.  If total distance is 180km what is the usual speed. 

2/3 * 180 =120


let the usual speed be x km/h
distance 120 km
time = 120/x   First part 

distance = 60 km  
speed = 3x/4

Time taken = 60/(3x/4)

=240/3x
=80/x  II part

120/x +80/x = 180/x + 1/2  ( 30 minutes =1/2)

200/x = 180/x +1/2

20/x = 1/2

x= 40 km/h






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