Question 1109679
When she rides her bike, she gets to her first classroom building 36 minutes faster than when she walks.
 If her average walking speed is 3 mph and her average biking speed is 12 mph, how far is it from her apartment to the classroom building? 
:
let d = dist from home to school
since we are dealing mph, change 36 min: 36/60 = .6 hrs
:
Write a time equation; time = dist/speed
:
Walk time - bike time = .6 hrs
{{{d/3}}} - {{{d/12}}} = .6
multiply by 12, cancel the denominators
4d - d = .6(12)
3d = 7.2
d = 7.2/3
d = 2.4 mi to the school
:
:
Check this, find the actual time each way
2.4/3 = .8 hrs
2.4/12 - .2 hrs
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time dif: .6 hrs which is 36 min