# SOLUTION: Please help me: A boy walked over hills at 3 kilometers per hour and on flat roads at 4 kilometers per hour. He walked 18 kilometers in 5 hours. How much of his trip was over hill

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 Question 139700: Please help me: A boy walked over hills at 3 kilometers per hour and on flat roads at 4 kilometers per hour. He walked 18 kilometers in 5 hours. How much of his trip was over hills? ThanksAnswer by josmiceli(9680)   (Show Source): You can put this solution on YOUR website!Let = km walked on hills Let = km walked on flat groun ------------------- Use substitution Multiply each side by 12 km km 6 km of the trip was over hills check answer: OK