Question 922344: How fast did a car go to overtake a passenger's bus in 5 hours if the bus' rate is 45 kph and left 4 hours before the car? Answer by richwmiller(17219) (Show Source):
You can put this solution on YOUR website! 5x=(5+4)*45
x=9*9
x=81 kph to catch it in 5 hours
another way
The first car had a head start of 180 (4*45) km
the second car needs to gain
180/5=36 km
so it must travel at
45+36=81 kph
check
Gaining speed 81-45= 36 mph
Head start 45*4 =180 miles
Time to catch up 180/36=5 hours
Algebraic solution
45(t+4)=81t
45t+180=81t
180=81t-45t
180=36t
t=5 hours
Distance to meeting 5*81=405 miles
