Question

a train takes 3hours less for a journey of 360 km if it's speed is increased by 10km/hr from it's usual speed.find usual speed of train.

Answer 1

30 km/h

Explanation:

usual speed= x km/h

increased speed= x +10 km/h

distance= 360 km

time difference= 3 h

• 360/x= 360/(x+10) +3
• 360/x= (360+ 3x+30)/(x+10)
• 360(x+10)= x(390+3x)
• 360x+3600= 390x+ 3x²
• 3x² + 30 x -3600=0
• x²+10x-1200=0
• x=30 km/h