Answers

2014-10-07T12:18:57+05:30
total distance = 240 km
let speed = x km/hr
therefore time = 240/x hrs
new speed = x-12 km/hr
therefore time = 240/x-12 hrs
given difference = 1 hr
therefore 240/x-12 - 240/x=1
240x-240x+2880/x2-12x =1
2880 = x2-12x
x2-12x-2880=0
by completing the squares
x=60 or x = -48
speed is non negetive 
therefore original speed of train = 60 km/hr



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