SOLUTION: Two cars leave City A at the same time to travel to City B. One car travels at 72km/h and the other at 78 km/h. If the slower car arrives 20 minutes after the faster car, how far a

Algebra ->  Customizable Word Problem Solvers  -> Travel -> SOLUTION: Two cars leave City A at the same time to travel to City B. One car travels at 72km/h and the other at 78 km/h. If the slower car arrives 20 minutes after the faster car, how far a      Log On

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Question 326912: Two cars leave City A at the same time to travel to City B. One car travels at 72km/h and the other at 78 km/h. If the slower car arrives 20 minutes after the faster car, how far apart are City A and City B?
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
Rate*Time=Distance
.
.
.
Ra=72kph
Rb=78kph
Car A,
Convert from minutes to hrs to be consistent with speed.
20 minutes=1%2F3 hr
1.72%2A%28t%2B1%2F3%29=D
.
.
.
Car B,
78%2At=D
2.t=D%2F78
.
.
Substitute eq. 2 into eq. 1,
72%28D%2F78%2B1%2F3%29=D
%2872%2F78%29D%2B26=D
D%281-12%2F13%29=26
D=26%2F%281%2F13%29
D=26%2A13
D=338km