SOLUTION: Richard Stewart commutes to work by first driving on country roads at an average speed of 45 miles per hour. He then drives on the interstate highway at an average speed of 75 mile

Question 907726: Richard Stewart commutes to work by first driving on country roads at an average speed of 45 miles per hour. He then drives on the interstate highway at an average speed of 75 miles or hour. Richards total commuting distance is 42 miles and his total commuting time is 0.6 hours. Determine the time Richard spends driving on country and the time he spends driving on the interstate highway.
Answer by lwsshak3(11628) (Show Source): You can put this solution on YOUR website!
Richard Stewart commutes to work by first driving on country roads at an average speed of 45 miles per hour. He then drives on the interstate highway at an average speed of 75 miles or hour. Richards total commuting distance is 42 miles and his total commuting time is 0.6 hours. Determine the time Richard spends driving on country and the time he spends driving on the interstate highway.
***
let x=distance Richard spends driving on country roads
42-x=distance Richard spends driving on the interstate highway
travel time=distance/speed
..

75x+45(42-x)=.6*45*75
75x+1890-45x=2025
30x=135
x=4.5 miles
42-x=37.5 miles
4.5/45=0.10
45/37.5=0.50
time Richard spends driving on country roads=0.10 hr
time Richard spends driving on the interstate highway=0.50 hr
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