If Katrina leaves now and drives 66km/h, she will reach Alton just in time for her appointment. On the other hand, if she has lunch first and leaves in 40 minutes, she will have to drive 90km/h to make her appointment. How far away is Alton?
How would you solve this problem? what confuses me is that it doesn't say what time her appointment is if she leaves now.
let her time if she left now be t hours
then the distance is 66t
if she left 40 minutes later, (2/3 of an hour), the calculation for the distance is
90(t-2/3)
the key is that the distance is the same, so
90(t-2/3) = 66t
90t - 60 = 66t
24t = 60
t = 2.5
put that into 66t to get 66(2.5) = 165 miles
(notice 2.5 hours is 150 minutes, so if she left later it would take her 110 minutes, which is 11/6 of an hour
(11/6)*90 = 165)