SOLUTION: A race car is traveling 40 km/hour faster than another on a race track. While the faster car travels 70 km, the second travels 60 km. find the speed of the faster car in km/hr.

Question 770019: A race car is traveling 40 km/hour faster than another on a race track. While the faster car travels 70 km, the second travels 60 km. find the speed of the faster car in km/hr.
Answer by josgarithmetic(39617) (Show Source): You can put this solution on YOUR website!
One of the keys is , "While the faster,... the second...". The amount of time is the same time interval. Call the time quantity, x hours.

CAR_________RATE_________TIME__________DISTANCE
Slow________r____________x_____________60
Fast_______r+40__________x_____________70

Make expressions for x for each car using r*t=d:
CAR_________RATE_________TIME__________DISTANCE
Slow________r____________60/r_____________60
Fast_______r+40__________70/(r+40)_____________70

The time quantities being equal, we just show the equation:
and solve for r.
... and of course, r+40.
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