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When going to the beach, Guilherme takes 2 hours on the road to go from his city to the beach and 3 hours to get back to his city. Knowing that Guilherme's car goes at 100 km/h when downhill, 80 km/h on plane surfaces and 50 km/h  uphill, and that there are only 8 kilometers of road on plane surface, what is the distance in kilometers between the city and the beach?

 Feb 14, 2022
 #1
avatar+251 
+3

Have you tried using the formula- \(d=st\) (or d=rt, whatever you want to call it); distance=speed*time.

 Feb 15, 2022
 #2
avatar+36417 
+1

 

For a round trip the uphill = downhill distances   and the flat = 16 km 

   so   U = D        Total roundtrip distance = U + U + F                                       U = uphill   D = downhill

 

U/100 + U/50   + 16 / 80 = 5 hours

(U + 2U) / 100 = 4.8

results in

U =160     and   F = 16    and  D = 160     ( roundtrip )

     total ONE-WAY distance =  (  160+160+ 16 )/ 2 = 168 km

 Feb 16, 2022

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