Question 485368
a man drives regularly from his office to his home when he drives 36 kph he arrives home 3 minutes late than usual.
 When he drives 45 kph he arrives 3 minutes earlier than usual.
 Find his usual driving time, and the distance from his office to his home?
:
Let t = his usual driving time
:
Change 3 min to hrs. {{{3/60}}} = .05 hrs
:
Write a dist equation, Dist = speed * time
:
45(t-.05) = 36(t+.05)
45t - 2.25 = 36t + 1.8
45t - 36t = 1.8 + 2.25
9t = 4.05
t = {{{4.05/9}}}
t = .45 hrs which is; .45(60) = 27 minutes, his normal driving time 
;
Find the distance when he is 3 min early (24 min)
45*{{{24/60}}} = 18 km
:
Check the distance when he is 3 min late (30 min)
36*{{{30/60}}} = 18 km
:
Summarize, 27 min normal drive time, 18 km is the distance