SOLUTION: Hello. I hope I am submitting this question in an appropriate category because I do ask that you please do help me. I'd greatly appreciate it. My question is as follows: Two

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: Hello. I hope I am submitting this question in an appropriate category because I do ask that you please do help me. I'd greatly appreciate it. My question is as follows: Two       Log On


   

Question 327600: Hello. I hope I am submitting this question in an appropriate category because I do ask that you please do help me. I'd greatly appreciate it.
My question is as follows:
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 min. after the faster car, how far apart are City A and City B?
I really appreciate any help you can give me, thank you so much!
Found 3 solutions by Fombitz, scott8148, edjones:
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
Rate*Time=Distance
.
.
.
Car 1:
1.78%2At=D
.
.
.
Car 2:
72%2A%28t%2B20%2F60%29=D
2.72%2A%28t%2B1%2F3%29=D
From eq.1,
t=D%2F78
Substitute into eq. 2,
72%2A%28D%2F78%2B1%2F3%29=D
%2812%2F13%29D%2B24=D
D-%2812%2F13%29D=24
%281%2F13%29D=24
D=312km

Answer by scott8148(6628) About Me  (Show Source):
You can put this solution on YOUR website!
time = distance / rate ___ working in hours

(d / 78) + (1/3) = (d / 72)

multiplying by (6 * 12 * 13) (the LCD) ___ 12d + 312 = 13d

312 = d

Answer by edjones(8007) About Me  (Show Source):
You can put this solution on YOUR website!
Let r=rare of speed, t=time in hrs, d=dist in kph.
rt=d
t=d/r
d/78 + 1/3 = d/72
936d/78 + 936/3 = 936d/72
12d+312=13d
d=312 km.
.
Ed