Posted by Calie on Sunday, June 1, 2008 at 5:24pm.
gregor is planning a driving trip where he knows that half his trip will be along major highways and part on country roads. The speed limit is 100km/h on highways and 60km/h on other roads. the total time he wants to spend driving is 12h. I set up the equation: 10h+6r=12, but I don't know how to solve for 3 more combinations of times gregor could spend driving on highways and country roads. please help

math  Damon, Sunday, June 1, 2008 at 5:51pm
He is going some distance, call it 2d
then
he goes 1d at 100 km/hr
and
he goes 1 d at 60 km/hr
time = distance / speed
so
d/100 + d/60 = 12
multiply both sides by 300
3 d + 5 d = 3600
8 d = 3600
d = 450
so
2 d = 900 km, the distance he goes
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