Question 389844
a car travels 20 km/h faster than a truck. The car covers 360 km in 3 hours less time than the truck. Find the speed of the truck. (Show your solution)
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speed of truck = x km/h
car speed = x+20 km/h
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time truck = 360/x
time car = 360/(x+20)
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time truck - time car = 3 hours
360/x-360/(x+20)=3
LCD= x(x+20)
(360(x+20)-360x)/(x(x+20)=3
360x+7200-360x=3x(x+20)
7200=3x^2+60x
3x^2+60x-7200=0
/3
x^2+20x-2400=0
x^2+60x-40x-2400=0
x(x+60)-40(x+60)=0
(x-40)(x+60)=0
x= 40 km/h the speed of truck
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