Rational Expressions: train traveled m miles to speed of s

[dbrown]

Thanks for this site, hope I can be helped. I do not understand algebra and I am taking class on line so it's a bit difficult.
Anyway, I have a problem that is as follows:

A train traveled m miles to a speed of s mph. A bus following the same route traveled 5 mph slower. Question: How much longer did the bus take than the train to make the trip? (Write the answer as a single rational expression.)

This is what I have so far: 2 different vehicles, 2 different equations (per instructor)
d1=r1*t1
d2=r2*t2
Distances are same, rates are different, solve for t2

This is were I am stuck. Please help, as soon as you can.
I do appreciate any help
Dorette

 

[Denis]

Re: Rational Expressions

The distances are the same: m miles
Let t = train time, b = bus time
m = st : t = m/s
m = (s-5)b : b = m/(s-5)

So difference = b - t = m/(s-5) - m/s
Just convert m/(s-5) - m/s to a single expression

 

[dbrown]

Re: Rational Expressions

The distances are the same: m miles
Let t = train time, b = bus time
m = st : t = m/s
m = (s-5)b : b = m/(s-5)

So difference = b - t = m/(s-5) - m/s
Just convert m/(s-5) - m/s to a single expression

Denis,
Thank you so much but I did the same thing and truned it in and instructor wanted the other way.
the way I posted the equation is how he suggested I worked it out. That is why I was stuck.
I got the same answer you did at first. Thanks so much. I will have to turn in something. Seeing
that it is due in 20 minutes or so. I so appreciate your quick response. I will be back I'm sure.
Have a great week.
DD

 

[Denis]

Re: Rational Expressions

This is what I have so far: 2 different vehicles, 2 different equations (per instructor)
d1=r1*t1
d2=r2*t2
Distances are same, rates are different, solve for t2
Dorette

Hmmm...something seems to be wrong with that instructor of yours :shock:

Since d1 = d2, then r2 * t2 = r1 * t1 ; solving for t2: t2 = r1 * t1 / r2
But WHY? You're asked for the difference in TIME, not for the value of t2.

 

[Deleted member 4993]

Re: Rational Expressions

The distances are the same: m miles

But Denis did it your instructor's way - he just called it by different name. I think there a "clear communication" problem.

Let t[sub:22qw1ji2]1[/sub:22qw1ji2] = train time, t[sub:22qw1ji2]2[/sub:22qw1ji2] = bus time
m = st[sub:22qw1ji2]1[/sub:22qw1ji2] ---> t[sub:22qw1ji2]1[/sub:22qw1ji2] = m/s
m = (s-5)t[sub:22qw1ji2]2[/sub:22qw1ji2] ---> t[sub:22qw1ji2]2[/sub:22qw1ji2] = m/(s-5)

So difference = t[sub:22qw1ji2]2[/sub:22qw1ji2] - t[sub:22qw1ji2]1[/sub:22qw1ji2] = m/(s-5) - m/s
Just convert m/(s-5) - m/s to a single expression