Question 389844
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Hi,        
Let r and t represent the speed and time for the truck
Write as we Read***  D = r*t for the truck and car
 r*t = 360km   r = 360km/t
(r+20kmph)(t-3hr) = 360km  substituting for r so as to solve for t
 (360/t + 20)(t-3) = 360km
 {{{(360 + 20t)/t*(t-3) = 360}}}
 {{{(360 + 20t)*(t-3) = 360t}}}
 360t + 20t^2 -3*360 -60t = 360t
        20t^2 -60t - 3*360 = 0
          t^2 -3t - 54 = 0
factoring
(t-9)(t+6) = 0 tossing out negative solution
  t = 9hr  r = 40kmph  for the truck

CHECKING our Answer for car:
 60kmph*6hr = 360km