Answer:
30 km/h
Step-by-step 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
