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A car travels 20kph faster than a truck. The car covers 480km in two hours less than
the time it takes the truck to travel the same distance. How fast does the car travel?
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Let x be the rate of the car, in miles per hour.
Then the rate of the truck is (x-20) mph.
The time for the car to travel 480 km is hpurs.
The time for the truck to travel 480 km is hours.
The "time" equation is
- = 2 hours.
You can solve this equation mentally by easy guess the answer x= 80.
Indeed, - = - = 8 - 6 = 2 hours.
Alternatively, you can solve equation (1) algebraically.
If you do it this way your first step is to multiply both sides by x*(x-20).
ANSWER. The car's rate is 80 km/h.
Solved.