Question 422304
Jackie either drives or bicycles from home to school.
 Her average speed when driving is 36mph, and her average speed when bicycling is 12mph.
 If it takes her 1/2 hour less to drive to school, how long does take her to go
 to school, and how far is the school from her home?
:
Let d = distance from home to school
:
Write a time equation; Time = dist/speed
:
Bike time - drive time = .5 hrs
{{{d/12}}} - {{{d/36}}} = .5
multiply by 36 to clear the denominators
36*{{{d/12}}} - 36*{{{d/36}}} = 36(.5)
Cancel the denominators
3d - d = 18
2d = 18
d = 9 mi is the distance
;
How long?
9/12 = 3/4 hr to bike
9/36 = 1/4 hr to drive
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differ: 1/2 hr